Bunches of new docs.

Type inference!

A new treatment of recursion combinator patterns.

docs/sphinx_docs/_build/html/_modules/joy/library.html

@@ -61,7 +61,7 @@
 <span class="kn">import</span> <span class="nn">operator</span><span class="o">,</span> <span class="nn">math</span>
 
 <span class="kn">from</span> <span class="nn">.parser</span> <span class="k">import</span> <span class="n">text_to_expression</span><span class="p">,</span> <span class="n">Symbol</span>
-<span class="kn">from</span> <span class="nn">.utils.stack</span> <span class="k">import</span> <span class="n">list_to_stack</span><span class="p">,</span> <span class="n">iter_stack</span><span class="p">,</span> <span class="n">pick</span><span class="p">,</span> <span class="n">pushback</span>
+<span class="kn">from</span> <span class="nn">.utils.stack</span> <span class="k">import</span> <span class="n">list_to_stack</span><span class="p">,</span> <span class="n">iter_stack</span><span class="p">,</span> <span class="n">pick</span><span class="p">,</span> <span class="n">concat</span>
 <span class="kn">from</span> <span class="nn">.utils.brutal_hackery</span> <span class="k">import</span> <span class="n">rename_code_object</span>
 
 
@@ -136,9 +136,9 @@
 <span class="s1">? == dup truthy</span>
 <span class="s1">dinfrirst == dip infra first</span>
 <span class="s1">nullary == [stack] dinfrirst</span>
-<span class="s1">unary == [stack [pop] dip] dinfrirst</span>
-<span class="s1">binary == [stack [popop] dip] dinfrirst</span>
-<span class="s1">ternary == [stack [popop pop] dip] dinfrirst</span>
+<span class="s1">unary == nullary popd</span>
+<span class="s1">binary == nullary [popop] dip</span>
+<span class="s1">ternary == unary [popop] dip</span>
 <span class="s1">pam == [i] map</span>
 <span class="s1">run == [] swap infra</span>
 <span class="s1">sqr == dup mul</span>
@@ -678,9 +678,9 @@
   <span class="k">return</span> <span class="n">res</span><span class="p">,</span> <span class="n">stack</span></div>
 
 
-<div class="viewcode-block" id="concat"><a class="viewcode-back" href="../../library.html#joy.library.concat">[docs]</a><span class="nd">@inscribe</span>
+<div class="viewcode-block" id="concat_"><a class="viewcode-back" href="../../library.html#joy.library.concat_">[docs]</a><span class="nd">@inscribe</span>
 <span class="nd">@SimpleFunctionWrapper</span>
-<span class="k">def</span> <span class="nf">concat</span><span class="p">(</span><span class="n">S</span><span class="p">):</span>
+<span class="k">def</span> <span class="nf">concat_</span><span class="p">(</span><span class="n">S</span><span class="p">):</span>
   <span class="sd">&#39;&#39;&#39;Concatinate the two lists on the top of the stack.</span>
 <span class="sd">  ::</span>
 
@@ -690,9 +690,7 @@
 
 <span class="sd">&#39;&#39;&#39;</span>
   <span class="p">(</span><span class="n">tos</span><span class="p">,</span> <span class="p">(</span><span class="n">second</span><span class="p">,</span> <span class="n">stack</span><span class="p">))</span> <span class="o">=</span> <span class="n">S</span>
-  <span class="k">for</span> <span class="n">term</span> <span class="ow">in</span> <span class="nb">reversed</span><span class="p">(</span><span class="nb">list</span><span class="p">(</span><span class="n">iter_stack</span><span class="p">(</span><span class="n">second</span><span class="p">))):</span>
-    <span class="n">tos</span> <span class="o">=</span> <span class="n">term</span><span class="p">,</span> <span class="n">tos</span>
-  <span class="k">return</span> <span class="n">tos</span><span class="p">,</span> <span class="n">stack</span></div>
+  <span class="k">return</span> <span class="n">concat</span><span class="p">(</span><span class="n">second</span><span class="p">,</span> <span class="n">tos</span><span class="p">),</span> <span class="n">stack</span></div>
 
 
 <div class="viewcode-block" id="shunt"><a class="viewcode-back" href="../../library.html#joy.library.shunt">[docs]</a><span class="nd">@inscribe</span>
@@ -963,7 +961,7 @@
 
 <span class="sd">  &#39;&#39;&#39;</span>
   <span class="n">quote</span><span class="p">,</span> <span class="n">stack</span> <span class="o">=</span> <span class="n">stack</span>
-  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">pushback</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="n">expression</span><span class="p">),</span> <span class="n">dictionary</span></div>
+  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">concat</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="n">expression</span><span class="p">),</span> <span class="n">dictionary</span></div>
 
 
 <div class="viewcode-block" id="x"><a class="viewcode-back" href="../../library.html#joy.library.x">[docs]</a><span class="nd">@inscribe</span>
@@ -980,7 +978,7 @@
 
 <span class="sd">  &#39;&#39;&#39;</span>
   <span class="n">quote</span><span class="p">,</span> <span class="n">_</span> <span class="o">=</span> <span class="n">stack</span>
-  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">pushback</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="n">expression</span><span class="p">),</span> <span class="n">dictionary</span></div>
+  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">concat</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="n">expression</span><span class="p">),</span> <span class="n">dictionary</span></div>
 
 
 <div class="viewcode-block" id="b"><a class="viewcode-back" href="../../library.html#joy.library.b">[docs]</a><span class="nd">@inscribe</span>
@@ -996,7 +994,7 @@
 
 <span class="sd">  &#39;&#39;&#39;</span>
   <span class="n">q</span><span class="p">,</span> <span class="p">(</span><span class="n">p</span><span class="p">,</span> <span class="p">(</span><span class="n">stack</span><span class="p">))</span> <span class="o">=</span> <span class="n">stack</span>
-  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">pushback</span><span class="p">(</span><span class="n">p</span><span class="p">,</span> <span class="n">pushback</span><span class="p">(</span><span class="n">q</span><span class="p">,</span> <span class="n">expression</span><span class="p">)),</span> <span class="n">dictionary</span></div>
+  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">concat</span><span class="p">(</span><span class="n">p</span><span class="p">,</span> <span class="n">concat</span><span class="p">(</span><span class="n">q</span><span class="p">,</span> <span class="n">expression</span><span class="p">)),</span> <span class="n">dictionary</span></div>
 
 
 <div class="viewcode-block" id="dupdip"><a class="viewcode-back" href="../../library.html#joy.library.dupdip">[docs]</a><span class="nd">@inscribe</span>
@@ -1015,7 +1013,7 @@
 <span class="sd">  &#39;&#39;&#39;</span>
   <span class="n">F</span><span class="p">,</span> <span class="n">stack</span> <span class="o">=</span> <span class="n">stack</span>
   <span class="n">a</span> <span class="o">=</span> <span class="n">stack</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span>
-  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">pushback</span><span class="p">(</span><span class="n">F</span><span class="p">,</span> <span class="p">(</span><span class="n">a</span><span class="p">,</span>  <span class="n">expression</span><span class="p">)),</span> <span class="n">dictionary</span></div>
+  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">concat</span><span class="p">(</span><span class="n">F</span><span class="p">,</span> <span class="p">(</span><span class="n">a</span><span class="p">,</span>  <span class="n">expression</span><span class="p">)),</span> <span class="n">dictionary</span></div>
 
 
 <div class="viewcode-block" id="infra"><a class="viewcode-back" href="../../library.html#joy.library.infra">[docs]</a><span class="nd">@inscribe</span>
@@ -1032,7 +1030,7 @@
 
 <span class="sd">  &#39;&#39;&#39;</span>
   <span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="p">(</span><span class="n">aggregate</span><span class="p">,</span> <span class="n">stack</span><span class="p">))</span> <span class="o">=</span> <span class="n">stack</span>
-  <span class="k">return</span> <span class="n">aggregate</span><span class="p">,</span> <span class="n">pushback</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="p">(</span><span class="n">stack</span><span class="p">,</span> <span class="p">(</span><span class="n">S_swaack</span><span class="p">,</span> <span class="n">expression</span><span class="p">))),</span> <span class="n">dictionary</span></div>
+  <span class="k">return</span> <span class="n">aggregate</span><span class="p">,</span> <span class="n">concat</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="p">(</span><span class="n">stack</span><span class="p">,</span> <span class="p">(</span><span class="n">S_swaack</span><span class="p">,</span> <span class="n">expression</span><span class="p">))),</span> <span class="n">dictionary</span></div>
 
 
 <div class="viewcode-block" id="genrec"><a class="viewcode-back" href="../../library.html#joy.library.genrec">[docs]</a><span class="nd">@inscribe</span>
@@ -1092,7 +1090,7 @@
   <span class="p">(</span><span class="n">rec2</span><span class="p">,</span> <span class="p">(</span><span class="n">rec1</span><span class="p">,</span> <span class="n">stack</span><span class="p">))</span> <span class="o">=</span> <span class="n">stack</span>
   <span class="p">(</span><span class="n">then</span><span class="p">,</span> <span class="p">(</span><span class="n">if_</span><span class="p">,</span> <span class="n">_</span><span class="p">))</span> <span class="o">=</span> <span class="n">stack</span>
   <span class="n">F</span> <span class="o">=</span> <span class="p">(</span><span class="n">if_</span><span class="p">,</span> <span class="p">(</span><span class="n">then</span><span class="p">,</span> <span class="p">(</span><span class="n">rec1</span><span class="p">,</span> <span class="p">(</span><span class="n">rec2</span><span class="p">,</span> <span class="p">(</span><span class="n">S_genrec</span><span class="p">,</span> <span class="p">())))))</span>
-  <span class="n">else_</span> <span class="o">=</span> <span class="n">pushback</span><span class="p">(</span><span class="n">rec1</span><span class="p">,</span> <span class="p">(</span><span class="n">F</span><span class="p">,</span> <span class="n">rec2</span><span class="p">))</span>
+  <span class="n">else_</span> <span class="o">=</span> <span class="n">concat</span><span class="p">(</span><span class="n">rec1</span><span class="p">,</span> <span class="p">(</span><span class="n">F</span><span class="p">,</span> <span class="n">rec2</span><span class="p">))</span>
   <span class="k">return</span> <span class="p">(</span><span class="n">else_</span><span class="p">,</span> <span class="n">stack</span><span class="p">),</span> <span class="p">(</span><span class="n">S_ifte</span><span class="p">,</span> <span class="n">expression</span><span class="p">),</span> <span class="n">dictionary</span></div>
 
 
@@ -1156,7 +1154,7 @@
 
 <span class="sd">  &#39;&#39;&#39;</span>
   <span class="p">(</span><span class="n">then</span><span class="p">,</span> <span class="p">(</span><span class="n">else_</span><span class="p">,</span> <span class="p">(</span><span class="n">flag</span><span class="p">,</span> <span class="n">stack</span><span class="p">)))</span> <span class="o">=</span> <span class="n">stack</span>
-  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">pushback</span><span class="p">(</span><span class="n">then</span> <span class="k">if</span> <span class="n">flag</span> <span class="k">else</span> <span class="n">else_</span><span class="p">,</span> <span class="n">expression</span><span class="p">),</span> <span class="n">dictionary</span></div>
+  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">concat</span><span class="p">(</span><span class="n">then</span> <span class="k">if</span> <span class="n">flag</span> <span class="k">else</span> <span class="n">else_</span><span class="p">,</span> <span class="n">expression</span><span class="p">),</span> <span class="n">dictionary</span></div>
 
 
 <div class="viewcode-block" id="ifte"><a class="viewcode-back" href="../../library.html#joy.library.ifte">[docs]</a><span class="nd">@inscribe</span>
@@ -1243,7 +1241,7 @@
 <span class="sd">  &#39;&#39;&#39;</span>
   <span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">stack</span><span class="p">))</span> <span class="o">=</span> <span class="n">stack</span>
   <span class="n">expression</span> <span class="o">=</span> <span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">expression</span><span class="p">)</span>
-  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">pushback</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="n">expression</span><span class="p">),</span> <span class="n">dictionary</span></div>
+  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">concat</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="n">expression</span><span class="p">),</span> <span class="n">dictionary</span></div>
 
 
 <div class="viewcode-block" id="dipd"><a class="viewcode-back" href="../../library.html#joy.library.dipd">[docs]</a><span class="nd">@inscribe</span>
@@ -1260,7 +1258,7 @@
 <span class="sd">  &#39;&#39;&#39;</span>
   <span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="p">(</span><span class="n">y</span><span class="p">,</span> <span class="n">stack</span><span class="p">)))</span> <span class="o">=</span> <span class="n">S</span>
   <span class="n">expression</span> <span class="o">=</span> <span class="p">(</span><span class="n">y</span><span class="p">,</span> <span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">expression</span><span class="p">))</span>
-  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">pushback</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="n">expression</span><span class="p">),</span> <span class="n">dictionary</span></div>
+  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">concat</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="n">expression</span><span class="p">),</span> <span class="n">dictionary</span></div>
 
 
 <div class="viewcode-block" id="dipdd"><a class="viewcode-back" href="../../library.html#joy.library.dipdd">[docs]</a><span class="nd">@inscribe</span>
@@ -1277,7 +1275,7 @@
 <span class="sd">  &#39;&#39;&#39;</span>
   <span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="p">(</span><span class="n">y</span><span class="p">,</span> <span class="p">(</span><span class="n">z</span><span class="p">,</span> <span class="n">stack</span><span class="p">))))</span> <span class="o">=</span> <span class="n">S</span>
   <span class="n">expression</span> <span class="o">=</span> <span class="p">(</span><span class="n">z</span><span class="p">,</span> <span class="p">(</span><span class="n">y</span><span class="p">,</span> <span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">expression</span><span class="p">)))</span>
-  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">pushback</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="n">expression</span><span class="p">),</span> <span class="n">dictionary</span></div>
+  <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">concat</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="n">expression</span><span class="p">),</span> <span class="n">dictionary</span></div>
 
 
 <div class="viewcode-block" id="app1"><a class="viewcode-back" href="../../library.html#joy.library.app1">[docs]</a><span class="nd">@inscribe</span>
@@ -1405,7 +1403,7 @@
   <span class="n">n</span> <span class="o">-=</span> <span class="mi">1</span>
   <span class="k">if</span> <span class="n">n</span><span class="p">:</span>
     <span class="n">expression</span> <span class="o">=</span> <span class="n">n</span><span class="p">,</span> <span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="p">(</span><span class="n">S_times</span><span class="p">,</span> <span class="n">expression</span><span class="p">))</span>
-  <span class="n">expression</span> <span class="o">=</span> <span class="n">pushback</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="n">expression</span><span class="p">)</span>
+  <span class="n">expression</span> <span class="o">=</span> <span class="n">concat</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="n">expression</span><span class="p">)</span>
   <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">expression</span><span class="p">,</span> <span class="n">dictionary</span></div>
 
 
@@ -1443,7 +1441,7 @@
 <span class="sd">  &#39;&#39;&#39;</span>
   <span class="n">quote</span><span class="p">,</span> <span class="p">(</span><span class="n">flag</span><span class="p">,</span> <span class="n">stack</span><span class="p">)</span> <span class="o">=</span> <span class="n">stack</span>
   <span class="k">if</span> <span class="n">flag</span><span class="p">:</span>
-    <span class="n">expression</span> <span class="o">=</span> <span class="n">pushback</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="p">(</span><span class="n">S_loop</span><span class="p">,</span> <span class="n">expression</span><span class="p">)))</span>
+    <span class="n">expression</span> <span class="o">=</span> <span class="n">concat</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="p">(</span><span class="n">S_loop</span><span class="p">,</span> <span class="n">expression</span><span class="p">)))</span>
   <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">expression</span><span class="p">,</span> <span class="n">dictionary</span></div>
 
 
@@ -1468,7 +1466,7 @@
 <span class="sd">                        L</span>
 <span class="sd">  &#39;&#39;&#39;</span>
   <span class="n">L</span><span class="p">,</span> <span class="p">(</span><span class="n">E</span><span class="p">,</span> <span class="p">(</span><span class="n">G</span><span class="p">,</span> <span class="p">(</span><span class="n">b</span><span class="p">,</span> <span class="p">(</span><span class="n">a</span><span class="p">,</span> <span class="n">stack</span><span class="p">))))</span> <span class="o">=</span> <span class="n">stack</span>
-  <span class="n">expression</span> <span class="o">=</span> <span class="n">pushback</span><span class="p">(</span><span class="n">G</span> <span class="k">if</span> <span class="n">a</span> <span class="o">&gt;</span> <span class="n">b</span> <span class="k">else</span> <span class="n">L</span> <span class="k">if</span> <span class="n">a</span> <span class="o">&lt;</span> <span class="n">b</span> <span class="k">else</span> <span class="n">E</span><span class="p">,</span> <span class="n">expression</span><span class="p">)</span>
+  <span class="n">expression</span> <span class="o">=</span> <span class="n">concat</span><span class="p">(</span><span class="n">G</span> <span class="k">if</span> <span class="n">a</span> <span class="o">&gt;</span> <span class="n">b</span> <span class="k">else</span> <span class="n">L</span> <span class="k">if</span> <span class="n">a</span> <span class="o">&lt;</span> <span class="n">b</span> <span class="k">else</span> <span class="n">E</span><span class="p">,</span> <span class="n">expression</span><span class="p">)</span>
   <span class="k">return</span> <span class="n">stack</span><span class="p">,</span> <span class="n">expression</span><span class="p">,</span> <span class="n">dictionary</span></div>
 
 

docs/sphinx_docs/_build/html/_modules/joy/utils/stack.html

@@ -175,7 +175,7 @@
   <span class="p">)</span>
 
 
-<div class="viewcode-block" id="pushback"><a class="viewcode-back" href="../../../stack.html#joy.utils.stack.pushback">[docs]</a><span class="k">def</span> <span class="nf">pushback</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="n">expression</span><span class="p">):</span>
+<div class="viewcode-block" id="concat"><a class="viewcode-back" href="../../../stack.html#joy.utils.stack.concat">[docs]</a><span class="k">def</span> <span class="nf">concat</span><span class="p">(</span><span class="n">quote</span><span class="p">,</span> <span class="n">expression</span><span class="p">):</span>
   <span class="sd">&#39;&#39;&#39;Concatinate quote onto expression.</span>
 
 <span class="sd">  In joy [1 2] [3 4] would become [1 2 3 4].</span>
@@ -188,7 +188,8 @@
   <span class="c1"># This is the fastest implementation, but will trigger</span>
   <span class="c1"># RuntimeError: maximum recursion depth exceeded</span>
   <span class="c1"># on quotes longer than sys.getrecursionlimit().</span>
-  <span class="k">return</span> <span class="p">(</span><span class="n">quote</span><span class="p">[</span><span class="mi">0</span><span class="p">],</span> <span class="n">pushback</span><span class="p">(</span><span class="n">quote</span><span class="p">[</span><span class="mi">1</span><span class="p">],</span> <span class="n">expression</span><span class="p">))</span> <span class="k">if</span> <span class="n">quote</span> <span class="k">else</span> <span class="n">expression</span></div>
+
+<span class="c1">##  return (quote[0], concat(quote[1], expression)) if quote else expression</span>
 
   <span class="c1"># Original implementation.</span>
 
@@ -197,13 +198,13 @@
   <span class="c1"># In-lining is slightly faster (and won&#39;t break the</span>
   <span class="c1"># recursion limit on long quotes.)</span>
 
-<span class="c1">##  temp = []</span>
-<span class="c1">##  while quote:</span>
-<span class="c1">##    item, quote = quote</span>
-<span class="c1">##    temp.append(item)</span>
-<span class="c1">##  for item in reversed(temp):</span>
-<span class="c1">##    expression = item, expression</span>
-<span class="c1">##  return expression</span>
+  <span class="n">temp</span> <span class="o">=</span> <span class="p">[]</span>
+  <span class="k">while</span> <span class="n">quote</span><span class="p">:</span>
+    <span class="n">item</span><span class="p">,</span> <span class="n">quote</span> <span class="o">=</span> <span class="n">quote</span>
+    <span class="n">temp</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">item</span><span class="p">)</span>
+  <span class="k">for</span> <span class="n">item</span> <span class="ow">in</span> <span class="nb">reversed</span><span class="p">(</span><span class="n">temp</span><span class="p">):</span>
+    <span class="n">expression</span> <span class="o">=</span> <span class="n">item</span><span class="p">,</span> <span class="n">expression</span>
+  <span class="k">return</span> <span class="n">expression</span></div>
 
 
 

docs/sphinx_docs/_build/html/genindex.html

@@ -104,7 +104,9 @@
 </li>
   </ul></td>
   <td style="width: 33%; vertical-align: top;"><ul>
-      <li><a href="library.html#joy.library.concat">concat() (in module joy.library)</a>
+      <li><a href="stack.html#joy.utils.stack.concat">concat() (in module joy.utils.stack)</a>
+</li>
+      <li><a href="library.html#joy.library.concat_">concat_() (in module joy.library)</a>
 </li>
       <li><a href="library.html#joy.library.cond">cond() (in module joy.library)</a>
 </li>
@@ -283,8 +285,6 @@
       <li><a href="library.html#joy.library.popop">popop() (in module joy.library)</a>
 </li>
       <li><a href="library.html#joy.library.pred">pred() (in module joy.library)</a>
-</li>
-      <li><a href="stack.html#joy.utils.stack.pushback">pushback() (in module joy.utils.stack)</a>
 </li>
   </ul></td>
 </tr></table>

docs/sphinx_docs/_build/html/index.html

@@ -132,13 +132,15 @@ interesting aspects.  It’s quite a treasure trove.</p>
 </li>
 <li class="toctree-l1"><a class="reference internal" href="notebooks/index.html">Essays about Programming in Joy</a><ul>
 <li class="toctree-l2"><a class="reference internal" href="notebooks/Developing.html">Developing a Program in Joy</a></li>
+<li class="toctree-l2"><a class="reference internal" href="notebooks/Quadratic.html">Quadratic formula</a></li>
 <li class="toctree-l2"><a class="reference internal" href="notebooks/Replacing.html">Replacing Functions in the Dictionary</a></li>
+<li class="toctree-l2"><a class="reference internal" href="notebooks/Recursion_Combinators.html">Recursive Combinators</a></li>
 <li class="toctree-l2"><a class="reference internal" href="notebooks/Ordered_Binary_Trees.html">Treating Trees I: Ordered Binary Trees</a></li>
 <li class="toctree-l2"><a class="reference internal" href="notebooks/Treestep.html">Treating Trees II: <code class="docutils literal notranslate"><span class="pre">treestep</span></code></a></li>
 <li class="toctree-l2"><a class="reference internal" href="notebooks/Generator_Programs.html">Using <code class="docutils literal notranslate"><span class="pre">x</span></code> to Generate Values</a></li>
 <li class="toctree-l2"><a class="reference internal" href="notebooks/Newton-Raphson.html">Newton’s method</a></li>
-<li class="toctree-l2"><a class="reference internal" href="notebooks/Quadratic.html">Quadratic formula</a></li>
 <li class="toctree-l2"><a class="reference internal" href="notebooks/Zipper.html">Traversing Datastructures with Zippers</a></li>
+<li class="toctree-l2"><a class="reference internal" href="notebooks/Types.html">Type Inference</a></li>
 <li class="toctree-l2"><a class="reference internal" href="notebooks/NoUpdates.html">No Updates</a></li>
 <li class="toctree-l2"><a class="reference internal" href="notebooks/Categorical.html">Categorical Programming</a></li>
 </ul>

docs/sphinx_docs/_build/html/library.html

@@ -214,8 +214,8 @@ one of the three depending on the results of comparing the two values:</p>
 </dd></dl>
 
 <dl class="function">
-<dt id="joy.library.concat">
-<code class="descclassname">joy.library.</code><code class="descname">concat</code><span class="sig-paren">(</span><em>stack</em>, <em>expression</em>, <em>dictionary</em><span class="sig-paren">)</span><a class="reference internal" href="_modules/joy/library.html#concat"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#joy.library.concat" title="Permalink to this definition">¶</a></dt>
+<dt id="joy.library.concat_">
+<code class="descclassname">joy.library.</code><code class="descname">concat_</code><span class="sig-paren">(</span><em>stack</em>, <em>expression</em>, <em>dictionary</em><span class="sig-paren">)</span><a class="reference internal" href="_modules/joy/library.html#concat_"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#joy.library.concat_" title="Permalink to this definition">¶</a></dt>
 <dd><p>Concatinate the two lists on the top of the stack.</p>
 <div class="highlight-default notranslate"><div class="highlight"><pre><span></span>   <span class="p">[</span><span class="n">a</span> <span class="n">b</span> <span class="n">c</span><span class="p">]</span> <span class="p">[</span><span class="n">d</span> <span class="n">e</span> <span class="n">f</span><span class="p">]</span> <span class="n">concat</span>
 <span class="o">----------------------------</span>

docs/sphinx_docs/_build/html/notebooks/Newton-Raphson.html

@@ -16,7 +16,7 @@
     <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
     <link rel="index" title="Index" href="../genindex.html" />
     <link rel="search" title="Search" href="../search.html" />
-    <link rel="next" title="Quadratic formula" href="Quadratic.html" />
+    <link rel="next" title="Traversing Datastructures with Zippers" href="Zipper.html" />
     <link rel="prev" title="Using x to Generate Values" href="Generator_Programs.html" />
    
   <link rel="stylesheet" href="../_static/custom.css" type="text/css" />
@@ -257,7 +257,7 @@ generated already and epsilon ε is handy on the stack…</p>
   <li><a href="../index.html">Documentation overview</a><ul>
   <li><a href="index.html">Essays about Programming in Joy</a><ul>
       <li>Previous: <a href="Generator_Programs.html" title="previous chapter">Using <code class="docutils literal notranslate"><span class="pre">x</span></code> to Generate Values</a></li>
-      <li>Next: <a href="Quadratic.html" title="next chapter">Quadratic formula</a></li>
+      <li>Next: <a href="Zipper.html" title="next chapter">Traversing Datastructures with Zippers</a></li>
   </ul></li>
   </ul></li>
 </ul>

docs/sphinx_docs/_build/html/notebooks/Quadratic.html

@@ -16,8 +16,8 @@
     <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
     <link rel="index" title="Index" href="../genindex.html" />
     <link rel="search" title="Search" href="../search.html" />
-    <link rel="next" title="Traversing Datastructures with Zippers" href="Zipper.html" />
-    <link rel="prev" title="Newton’s method" href="Newton-Raphson.html" />
+    <link rel="next" title="Replacing Functions in the Dictionary" href="Replacing.html" />
+    <link rel="prev" title="Developing a Program in Joy" href="Developing.html" />
    
   <link rel="stylesheet" href="../_static/custom.css" type="text/css" />
   
@@ -32,156 +32,136 @@
         <div class="bodywrapper">
           <div class="body" role="main">
             
-  <div class="section" id="quadratic-formula">
-<h1><a class="reference external" href="https://en.wikipedia.org/wiki/Quadratic_formula">Quadratic formula</a><a class="headerlink" href="#quadratic-formula" title="Permalink to this headline">¶</a></h1>
-<div class="code ipython2 highlight-default notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">notebook_preamble</span> <span class="k">import</span> <span class="n">J</span><span class="p">,</span> <span class="n">V</span><span class="p">,</span> <span class="n">define</span>
+  <div class="code ipython2 highlight-default notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">notebook_preamble</span> <span class="k">import</span> <span class="n">J</span><span class="p">,</span> <span class="n">V</span><span class="p">,</span> <span class="n">define</span>
 </pre></div>
 </div>
+<div class="section" id="quadratic-formula">
+<h1><a class="reference external" href="https://en.wikipedia.org/wiki/Quadratic_formula">Quadratic formula</a><a class="headerlink" href="#quadratic-formula" title="Permalink to this headline">¶</a></h1>
 <p>Cf.
 <a class="reference external" href="http://www.kevinalbrecht.com/code/joy-mirror/jp-quadratic.html">jp-quadratic.html</a></p>
-<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="o">-</span><span class="n">b</span>  <span class="o">+/-</span> <span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span> <span class="o">-</span> <span class="mi">4</span> <span class="o">*</span> <span class="n">a</span> <span class="o">*</span> <span class="n">c</span><span class="p">)</span>
-<span class="o">-----------------------------</span>
-           <span class="mi">2</span> <span class="o">*</span> <span class="n">a</span>
+<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>   -b ± sqrt(b^2 - 4 * a * c)
+--------------------------------
+            2 * a
 </pre></div>
 </div>
 <p><span class="math notranslate nohighlight">\(\frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\)</span></p>
 <div class="section" id="write-a-straightforward-program-with-variable-names">
 <h2>Write a straightforward program with variable names.<a class="headerlink" href="#write-a-straightforward-program-with-variable-names" title="Permalink to this headline">¶</a></h2>
-<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">b</span> <span class="n">neg</span> <span class="n">b</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="n">a</span> <span class="n">c</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="p">[</span><span class="o">+</span><span class="p">]</span> <span class="p">[</span><span class="o">-</span><span class="p">]</span> <span class="n">cleave</span> <span class="n">a</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+<p>This math translates to Joy code in a straightforward manner. We are
+going to use named variables to keep track of the arguments, then write
+a definition without them.</p>
+<div class="section" id="b">
+<h3><code class="docutils literal notranslate"><span class="pre">-b</span></code><a class="headerlink" href="#b" title="Permalink to this headline">¶</a></h3>
+<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">b</span> <span class="n">neg</span>
 </pre></div>
 </div>
-<p>We use <code class="docutils literal notranslate"><span class="pre">cleave</span></code> to compute the sum and difference and then <code class="docutils literal notranslate"><span class="pre">app2</span></code> to
-finish computing both roots using a quoted program <code class="docutils literal notranslate"><span class="pre">[2a</span> <span class="pre">truediv]</span></code>
-built with <code class="docutils literal notranslate"><span class="pre">cons</span></code>.</p>
-<div class="section" id="check-it">
-<h3>Check it.<a class="headerlink" href="#check-it" title="Permalink to this headline">¶</a></h3>
-<p>Evaluating by hand:</p>
-<div class="highlight-default notranslate"><div class="highlight"><pre><span></span> <span class="n">b</span> <span class="n">neg</span> <span class="n">b</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="n">a</span> <span class="n">c</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="p">[</span><span class="o">+</span><span class="p">]</span> <span class="p">[</span><span class="o">-</span><span class="p">]</span> <span class="n">cleave</span> <span class="n">a</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-<span class="o">-</span><span class="n">b</span>     <span class="n">b</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="n">a</span> <span class="n">c</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="p">[</span><span class="o">+</span><span class="p">]</span> <span class="p">[</span><span class="o">-</span><span class="p">]</span> <span class="n">cleave</span> <span class="n">a</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-<span class="o">-</span><span class="n">b</span>     <span class="n">b</span><span class="o">^</span><span class="mi">2</span>   <span class="mi">4</span> <span class="n">a</span> <span class="n">c</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="p">[</span><span class="o">+</span><span class="p">]</span> <span class="p">[</span><span class="o">-</span><span class="p">]</span> <span class="n">cleave</span> <span class="n">a</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-<span class="o">-</span><span class="n">b</span>     <span class="n">b</span><span class="o">^</span><span class="mi">2</span> <span class="mi">4</span><span class="n">ac</span>         <span class="o">-</span> <span class="n">sqrt</span> <span class="p">[</span><span class="o">+</span><span class="p">]</span> <span class="p">[</span><span class="o">-</span><span class="p">]</span> <span class="n">cleave</span> <span class="n">a</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-<span class="o">-</span><span class="n">b</span>     <span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span>           <span class="n">sqrt</span> <span class="p">[</span><span class="o">+</span><span class="p">]</span> <span class="p">[</span><span class="o">-</span><span class="p">]</span> <span class="n">cleave</span> <span class="n">a</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-<span class="o">-</span><span class="n">b</span> <span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span><span class="p">)</span>              <span class="p">[</span><span class="o">+</span><span class="p">]</span> <span class="p">[</span><span class="o">-</span><span class="p">]</span> <span class="n">cleave</span> <span class="n">a</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-
-<span class="o">-</span><span class="n">b</span> <span class="o">-</span><span class="n">b</span><span class="o">+</span><span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span><span class="p">)</span>    <span class="o">-</span><span class="n">b</span><span class="o">-</span><span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span><span class="p">)</span>    <span class="n">a</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-<span class="o">-</span><span class="n">b</span> <span class="o">-</span><span class="n">b</span><span class="o">+</span><span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span><span class="p">)</span>    <span class="o">-</span><span class="n">b</span><span class="o">-</span><span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span><span class="p">)</span>    <span class="mi">2</span><span class="n">a</span>    <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-<span class="o">-</span><span class="n">b</span> <span class="o">-</span><span class="n">b</span><span class="o">+</span><span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span><span class="p">)</span>    <span class="o">-</span><span class="n">b</span><span class="o">-</span><span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span><span class="p">)</span>    <span class="p">[</span><span class="mi">2</span><span class="n">a</span> <span class="n">truediv</span><span class="p">]</span>         <span class="n">app2</span>
-<span class="o">-</span><span class="n">b</span> <span class="o">-</span><span class="n">b</span><span class="o">+</span><span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span><span class="p">)</span><span class="o">/</span><span class="mi">2</span><span class="n">a</span> <span class="o">-</span><span class="n">b</span><span class="o">-</span><span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span><span class="p">)</span><span class="o">/</span><span class="mi">2</span><span class="n">a</span>
+</div>
+<div class="section" id="sqrt-b-2-4-a-c">
+<h3><code class="docutils literal notranslate"><span class="pre">sqrt(b^2</span> <span class="pre">-</span> <span class="pre">4</span> <span class="pre">*</span> <span class="pre">a</span> <span class="pre">*</span> <span class="pre">c)</span></code><a class="headerlink" href="#sqrt-b-2-4-a-c" title="Permalink to this headline">¶</a></h3>
+<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">b</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="n">a</span> <span class="n">c</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span>
 </pre></div>
 </div>
-<p>(Eventually we’ll be able to use e.g. Sympy versions of the Joy commands
-to do this sort of thing symbolically. This is part of what is meant by
-a “categorical” language.)</p>
 </div>
-<div class="section" id="cleanup">
-<h3>Cleanup<a class="headerlink" href="#cleanup" title="Permalink to this headline">¶</a></h3>
-<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="o">-</span><span class="n">b</span> <span class="o">-</span><span class="n">b</span><span class="o">+</span><span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span><span class="p">)</span><span class="o">/</span><span class="mi">2</span><span class="n">a</span> <span class="o">-</span><span class="n">b</span><span class="o">-</span><span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span><span class="p">)</span><span class="o">/</span><span class="mi">2</span><span class="n">a</span>                          <span class="n">roll</span><span class="o">&lt;</span> <span class="n">pop</span>
-   <span class="o">-</span><span class="n">b</span><span class="o">+</span><span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span><span class="p">)</span><span class="o">/</span><span class="mi">2</span><span class="n">a</span> <span class="o">-</span><span class="n">b</span><span class="o">-</span><span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span><span class="p">)</span><span class="o">/</span><span class="mi">2</span><span class="n">a</span> <span class="o">-</span><span class="n">b</span>                             <span class="n">pop</span>
-   <span class="o">-</span><span class="n">b</span><span class="o">+</span><span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span><span class="p">)</span><span class="o">/</span><span class="mi">2</span><span class="n">a</span> <span class="o">-</span><span class="n">b</span><span class="o">-</span><span class="n">sqrt</span><span class="p">(</span><span class="n">b</span><span class="o">^</span><span class="mi">2</span><span class="o">-</span><span class="mi">4</span><span class="n">ac</span><span class="p">)</span><span class="o">/</span><span class="mi">2</span><span class="n">a</span>
+<div class="section" id="a">
+<h3><code class="docutils literal notranslate"><span class="pre">/2a</span></code><a class="headerlink" href="#a" title="Permalink to this headline">¶</a></h3>
+<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">a</span> <span class="mi">2</span> <span class="o">*</span> <span class="o">/</span>
 </pre></div>
 </div>
 </div>
+<div class="section" id="id1">
+<h3><code class="docutils literal notranslate"><span class="pre">±</span></code><a class="headerlink" href="#id1" title="Permalink to this headline">¶</a></h3>
+<p>There is a function <code class="docutils literal notranslate"><span class="pre">pm</span></code> that accepts two values on the stack and
+replaces them with their sum and difference.</p>
+<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">pm</span> <span class="o">==</span> <span class="p">[</span><span class="o">+</span><span class="p">]</span> <span class="p">[</span><span class="o">-</span><span class="p">]</span> <span class="n">cleave</span> <span class="n">popdd</span>
+</pre></div>
+</div>
+</div>
+<div class="section" id="putting-them-together">
+<h3>Putting Them Together<a class="headerlink" href="#putting-them-together" title="Permalink to this headline">¶</a></h3>
+<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">b</span> <span class="n">neg</span> <span class="n">b</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="n">a</span> <span class="n">c</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="n">a</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+</pre></div>
+</div>
+<p>We use <code class="docutils literal notranslate"><span class="pre">app2</span></code> to compute both roots by using a quoted program
+<code class="docutils literal notranslate"><span class="pre">[2a</span> <span class="pre">/]</span></code> built with <code class="docutils literal notranslate"><span class="pre">cons</span></code>.</p>
+</div>
 </div>
 <div class="section" id="derive-a-definition">
 <h2>Derive a definition.<a class="headerlink" href="#derive-a-definition" title="Permalink to this headline">¶</a></h2>
-<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">b</span> <span class="n">neg</span> <span class="n">b</span>           <span class="n">sqr</span> <span class="mi">4</span> <span class="n">a</span> <span class="n">c</span>        <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="p">[</span><span class="o">+</span><span class="p">]</span> <span class="p">[</span><span class="o">-</span><span class="p">]</span> <span class="n">cleave</span> <span class="n">a</span>       <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span> <span class="n">roll</span><span class="o">&lt;</span> <span class="n">pop</span>
-<span class="n">b</span>    <span class="p">[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="n">a</span> <span class="n">c</span>        <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="p">[</span><span class="o">+</span><span class="p">]</span> <span class="p">[</span><span class="o">-</span><span class="p">]</span> <span class="n">cleave</span> <span class="n">a</span>       <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span> <span class="n">roll</span><span class="o">&lt;</span> <span class="n">pop</span>
-<span class="n">b</span> <span class="n">a</span> <span class="n">c</span>    <span class="p">[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="p">[</span><span class="o">+</span><span class="p">]</span> <span class="p">[</span><span class="o">-</span><span class="p">]</span> <span class="n">cleave</span> <span class="n">a</span>       <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span> <span class="n">roll</span><span class="o">&lt;</span> <span class="n">pop</span>
-<span class="n">b</span> <span class="n">a</span> <span class="n">c</span> <span class="n">a</span>    <span class="p">[[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="p">[</span><span class="o">+</span><span class="p">]</span> <span class="p">[</span><span class="o">-</span><span class="p">]</span> <span class="n">cleave</span><span class="p">]</span> <span class="n">dip</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span> <span class="n">roll</span><span class="o">&lt;</span> <span class="n">pop</span>
-<span class="n">b</span> <span class="n">a</span> <span class="n">c</span> <span class="n">over</span> <span class="p">[[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="p">[</span><span class="o">+</span><span class="p">]</span> <span class="p">[</span><span class="o">-</span><span class="p">]</span> <span class="n">cleave</span><span class="p">]</span> <span class="n">dip</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span> <span class="n">roll</span><span class="o">&lt;</span> <span class="n">pop</span>
+<p>Working backwards we use <code class="docutils literal notranslate"><span class="pre">dip</span></code> and <code class="docutils literal notranslate"><span class="pre">dipd</span></code> to extract the code from
+the variables:</p>
+<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">b</span>             <span class="n">neg</span>  <span class="n">b</span>      <span class="n">sqr</span> <span class="mi">4</span> <span class="n">a</span> <span class="n">c</span>   <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="n">a</span>    <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+<span class="n">b</span>            <span class="p">[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="n">a</span> <span class="n">c</span>   <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="n">a</span>    <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+<span class="n">b</span> <span class="n">a</span> <span class="n">c</span>       <span class="p">[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="n">a</span>    <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+<span class="n">b</span> <span class="n">a</span> <span class="n">c</span> <span class="n">a</span>    <span class="p">[[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span><span class="p">]</span> <span class="n">dip</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+<span class="n">b</span> <span class="n">a</span> <span class="n">c</span> <span class="n">over</span> <span class="p">[[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span><span class="p">]</span> <span class="n">dip</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
 </pre></div>
 </div>
-<div class="code ipython2 highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">define</span><span class="p">(</span><span class="s1">&#39;quadratic == over [[[neg] dupdip sqr 4] dipd * * - sqrt [+] [-] cleave] dip 2 * [truediv] cons app2 roll&lt; pop&#39;</span><span class="p">)</span>
+<p>The three arguments are to the left, so we can “chop off” everything to
+the right and say it’s the definition of the <code class="docutils literal notranslate"><span class="pre">quadratic</span></code> function:</p>
+<div class="code ipython2 highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">define</span><span class="p">(</span><span class="s1">&#39;quadratic == over [[[neg] dupdip sqr 4] dipd * * - sqrt pm] dip 2 * [/] cons app2&#39;</span><span class="p">)</span>
 </pre></div>
 </div>
+<p>Let’s try it out:</p>
 <div class="code ipython2 highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">J</span><span class="p">(</span><span class="s1">&#39;3 1 1 quadratic&#39;</span><span class="p">)</span>
 </pre></div>
 </div>
 <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="o">-</span><span class="mf">0.3819660112501051</span> <span class="o">-</span><span class="mf">2.618033988749895</span>
 </pre></div>
 </div>
-</div>
-<div class="section" id="simplify">
-<h2>Simplify<a class="headerlink" href="#simplify" title="Permalink to this headline">¶</a></h2>
-<p>We can define a <code class="docutils literal notranslate"><span class="pre">pm</span></code> plus-or-minus function:</p>
-<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">pm</span> <span class="o">==</span> <span class="p">[</span><span class="o">+</span><span class="p">]</span> <span class="p">[</span><span class="o">-</span><span class="p">]</span> <span class="n">cleave</span> <span class="n">popdd</span>
+<p>If you look at the Joy evaluation trace you can see that the first few
+lines are the <code class="docutils literal notranslate"><span class="pre">dip</span></code> and <code class="docutils literal notranslate"><span class="pre">dipd</span></code> combinators building the main program
+by incorporating the values on the stack. Then that program runs and you
+get the results. This is pretty typical of Joy code.</p>
+<div class="code ipython2 highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">V</span><span class="p">(</span><span class="s1">&#39;-5 1 4 quadratic&#39;</span><span class="p">)</span>
 </pre></div>
 </div>
-<p>Then <code class="docutils literal notranslate"><span class="pre">quadratic</span></code> becomes:</p>
-<div class="code ipython2 highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">define</span><span class="p">(</span><span class="s1">&#39;quadratic == over [[[neg] dupdip sqr 4] dipd * * - sqrt pm] dip 2 * [truediv] cons app2&#39;</span><span class="p">)</span>
+<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>                                                   <span class="o">.</span> <span class="o">-</span><span class="mi">5</span> <span class="mi">1</span> <span class="mi">4</span> <span class="n">quadratic</span>
+                                                <span class="o">-</span><span class="mi">5</span> <span class="o">.</span> <span class="mi">1</span> <span class="mi">4</span> <span class="n">quadratic</span>
+                                              <span class="o">-</span><span class="mi">5</span> <span class="mi">1</span> <span class="o">.</span> <span class="mi">4</span> <span class="n">quadratic</span>
+                                            <span class="o">-</span><span class="mi">5</span> <span class="mi">1</span> <span class="mi">4</span> <span class="o">.</span> <span class="n">quadratic</span>
+                                            <span class="o">-</span><span class="mi">5</span> <span class="mi">1</span> <span class="mi">4</span> <span class="o">.</span> <span class="n">over</span> <span class="p">[[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span><span class="p">]</span> <span class="n">dip</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                          <span class="o">-</span><span class="mi">5</span> <span class="mi">1</span> <span class="mi">4</span> <span class="mi">1</span> <span class="o">.</span> <span class="p">[[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span><span class="p">]</span> <span class="n">dip</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+<span class="o">-</span><span class="mi">5</span> <span class="mi">1</span> <span class="mi">4</span> <span class="mi">1</span> <span class="p">[[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span><span class="p">]</span> <span class="o">.</span> <span class="n">dip</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                            <span class="o">-</span><span class="mi">5</span> <span class="mi">1</span> <span class="mi">4</span> <span class="o">.</span> <span class="p">[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                       <span class="o">-</span><span class="mi">5</span> <span class="mi">1</span> <span class="mi">4</span> <span class="p">[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="o">.</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                                <span class="o">-</span><span class="mi">5</span> <span class="o">.</span> <span class="p">[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">4</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                          <span class="o">-</span><span class="mi">5</span> <span class="p">[</span><span class="n">neg</span><span class="p">]</span> <span class="o">.</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">4</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                                <span class="o">-</span><span class="mi">5</span> <span class="o">.</span> <span class="n">neg</span> <span class="o">-</span><span class="mi">5</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">4</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                                 <span class="mi">5</span> <span class="o">.</span> <span class="o">-</span><span class="mi">5</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">4</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                              <span class="mi">5</span> <span class="o">-</span><span class="mi">5</span> <span class="o">.</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">4</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                              <span class="mi">5</span> <span class="o">-</span><span class="mi">5</span> <span class="o">.</span> <span class="n">dup</span> <span class="n">mul</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">4</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                           <span class="mi">5</span> <span class="o">-</span><span class="mi">5</span> <span class="o">-</span><span class="mi">5</span> <span class="o">.</span> <span class="n">mul</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">4</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                              <span class="mi">5</span> <span class="mi">25</span> <span class="o">.</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">4</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                            <span class="mi">5</span> <span class="mi">25</span> <span class="mi">4</span> <span class="o">.</span> <span class="mi">1</span> <span class="mi">4</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                          <span class="mi">5</span> <span class="mi">25</span> <span class="mi">4</span> <span class="mi">1</span> <span class="o">.</span> <span class="mi">4</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                        <span class="mi">5</span> <span class="mi">25</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">4</span> <span class="o">.</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                          <span class="mi">5</span> <span class="mi">25</span> <span class="mi">4</span> <span class="mi">4</span> <span class="o">.</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                           <span class="mi">5</span> <span class="mi">25</span> <span class="mi">16</span> <span class="o">.</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                               <span class="mi">5</span> <span class="mi">9</span> <span class="o">.</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                             <span class="mi">5</span> <span class="mf">3.0</span> <span class="o">.</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                           <span class="mf">8.0</span> <span class="mf">2.0</span> <span class="o">.</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                         <span class="mf">8.0</span> <span class="mf">2.0</span> <span class="mi">1</span> <span class="o">.</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                       <span class="mf">8.0</span> <span class="mf">2.0</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">.</span> <span class="o">*</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                         <span class="mf">8.0</span> <span class="mf">2.0</span> <span class="mi">2</span> <span class="o">.</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
+                                     <span class="mf">8.0</span> <span class="mf">2.0</span> <span class="mi">2</span> <span class="p">[</span><span class="o">/</span><span class="p">]</span> <span class="o">.</span> <span class="n">cons</span> <span class="n">app2</span>
+                                     <span class="mf">8.0</span> <span class="mf">2.0</span> <span class="p">[</span><span class="mi">2</span> <span class="o">/</span><span class="p">]</span> <span class="o">.</span> <span class="n">app2</span>
+                                       <span class="p">[</span><span class="mf">8.0</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="o">/</span><span class="p">]</span> <span class="o">.</span> <span class="n">infra</span> <span class="n">first</span> <span class="p">[</span><span class="mf">2.0</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="o">/</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
+                                               <span class="mf">8.0</span> <span class="o">.</span> <span class="mi">2</span> <span class="o">/</span> <span class="p">[]</span> <span class="n">swaack</span> <span class="n">first</span> <span class="p">[</span><span class="mf">2.0</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="o">/</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
+                                             <span class="mf">8.0</span> <span class="mi">2</span> <span class="o">.</span> <span class="o">/</span> <span class="p">[]</span> <span class="n">swaack</span> <span class="n">first</span> <span class="p">[</span><span class="mf">2.0</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="o">/</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
+                                               <span class="mf">4.0</span> <span class="o">.</span> <span class="p">[]</span> <span class="n">swaack</span> <span class="n">first</span> <span class="p">[</span><span class="mf">2.0</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="o">/</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
+                                            <span class="mf">4.0</span> <span class="p">[]</span> <span class="o">.</span> <span class="n">swaack</span> <span class="n">first</span> <span class="p">[</span><span class="mf">2.0</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="o">/</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
+                                             <span class="p">[</span><span class="mf">4.0</span><span class="p">]</span> <span class="o">.</span> <span class="n">first</span> <span class="p">[</span><span class="mf">2.0</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="o">/</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
+                                               <span class="mf">4.0</span> <span class="o">.</span> <span class="p">[</span><span class="mf">2.0</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="o">/</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
+                                         <span class="mf">4.0</span> <span class="p">[</span><span class="mf">2.0</span><span class="p">]</span> <span class="o">.</span> <span class="p">[</span><span class="mi">2</span> <span class="o">/</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
+                                   <span class="mf">4.0</span> <span class="p">[</span><span class="mf">2.0</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="o">/</span><span class="p">]</span> <span class="o">.</span> <span class="n">infra</span> <span class="n">first</span>
+                                               <span class="mf">2.0</span> <span class="o">.</span> <span class="mi">2</span> <span class="o">/</span> <span class="p">[</span><span class="mf">4.0</span><span class="p">]</span> <span class="n">swaack</span> <span class="n">first</span>
+                                             <span class="mf">2.0</span> <span class="mi">2</span> <span class="o">.</span> <span class="o">/</span> <span class="p">[</span><span class="mf">4.0</span><span class="p">]</span> <span class="n">swaack</span> <span class="n">first</span>
+                                               <span class="mf">1.0</span> <span class="o">.</span> <span class="p">[</span><span class="mf">4.0</span><span class="p">]</span> <span class="n">swaack</span> <span class="n">first</span>
+                                         <span class="mf">1.0</span> <span class="p">[</span><span class="mf">4.0</span><span class="p">]</span> <span class="o">.</span> <span class="n">swaack</span> <span class="n">first</span>
+                                         <span class="mf">4.0</span> <span class="p">[</span><span class="mf">1.0</span><span class="p">]</span> <span class="o">.</span> <span class="n">first</span>
+                                           <span class="mf">4.0</span> <span class="mf">1.0</span> <span class="o">.</span>
 </pre></div>
 </div>
-<div class="code ipython2 highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">J</span><span class="p">(</span><span class="s1">&#39;3 1 1 quadratic&#39;</span><span class="p">)</span>
-</pre></div>
-</div>
-<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="o">-</span><span class="mf">0.3819660112501051</span> <span class="o">-</span><span class="mf">2.618033988749895</span>
-</pre></div>
-</div>
-<div class="section" id="define-a-native-pm-function">
-<h3>Define a “native” <code class="docutils literal notranslate"><span class="pre">pm</span></code> function.<a class="headerlink" href="#define-a-native-pm-function" title="Permalink to this headline">¶</a></h3>
-<p>The definition of <code class="docutils literal notranslate"><span class="pre">pm</span></code> above is pretty elegant, but the implementation
-takes a lot of steps relative to what it’s accomplishing. Since we are
-likely to use <code class="docutils literal notranslate"><span class="pre">pm</span></code> more than once in the future, let’s write a
-primitive in Python and add it to the dictionary. (This has been done
-already.)</p>
-<div class="code ipython2 highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">def</span> <span class="nf">pm</span><span class="p">(</span><span class="n">stack</span><span class="p">):</span>
-    <span class="n">a</span><span class="p">,</span> <span class="p">(</span><span class="n">b</span><span class="p">,</span> <span class="n">stack</span><span class="p">)</span> <span class="o">=</span> <span class="n">stack</span>
-    <span class="n">p</span><span class="p">,</span> <span class="n">m</span><span class="p">,</span> <span class="o">=</span> <span class="n">b</span> <span class="o">+</span> <span class="n">a</span><span class="p">,</span> <span class="n">b</span> <span class="o">-</span> <span class="n">a</span>
-    <span class="k">return</span> <span class="n">m</span><span class="p">,</span> <span class="p">(</span><span class="n">p</span><span class="p">,</span> <span class="n">stack</span><span class="p">)</span>
-</pre></div>
-</div>
-<p>The resulting trace is short enough to fit on a page.</p>
-<div class="code ipython2 highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">V</span><span class="p">(</span><span class="s1">&#39;3 1 1 quadratic&#39;</span><span class="p">)</span>
-</pre></div>
-</div>
-<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>                                                    <span class="o">.</span> <span class="mi">3</span> <span class="mi">1</span> <span class="mi">1</span> <span class="n">quadratic</span>
-                                                  <span class="mi">3</span> <span class="o">.</span> <span class="mi">1</span> <span class="mi">1</span> <span class="n">quadratic</span>
-                                                <span class="mi">3</span> <span class="mi">1</span> <span class="o">.</span> <span class="mi">1</span> <span class="n">quadratic</span>
-                                              <span class="mi">3</span> <span class="mi">1</span> <span class="mi">1</span> <span class="o">.</span> <span class="n">quadratic</span>
-                                              <span class="mi">3</span> <span class="mi">1</span> <span class="mi">1</span> <span class="o">.</span> <span class="n">over</span> <span class="p">[[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span><span class="p">]</span> <span class="n">dip</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                            <span class="mi">3</span> <span class="mi">1</span> <span class="mi">1</span> <span class="mi">1</span> <span class="o">.</span> <span class="p">[[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span><span class="p">]</span> <span class="n">dip</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-  <span class="mi">3</span> <span class="mi">1</span> <span class="mi">1</span> <span class="mi">1</span> <span class="p">[[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span><span class="p">]</span> <span class="o">.</span> <span class="n">dip</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                              <span class="mi">3</span> <span class="mi">1</span> <span class="mi">1</span> <span class="o">.</span> <span class="p">[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                         <span class="mi">3</span> <span class="mi">1</span> <span class="mi">1</span> <span class="p">[[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span><span class="p">]</span> <span class="o">.</span> <span class="n">dipd</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                                  <span class="mi">3</span> <span class="o">.</span> <span class="p">[</span><span class="n">neg</span><span class="p">]</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">1</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                            <span class="mi">3</span> <span class="p">[</span><span class="n">neg</span><span class="p">]</span> <span class="o">.</span> <span class="n">dupdip</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">1</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                                  <span class="mi">3</span> <span class="o">.</span> <span class="n">neg</span> <span class="mi">3</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">1</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                                 <span class="o">-</span><span class="mi">3</span> <span class="o">.</span> <span class="mi">3</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">1</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                               <span class="o">-</span><span class="mi">3</span> <span class="mi">3</span> <span class="o">.</span> <span class="n">sqr</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">1</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                               <span class="o">-</span><span class="mi">3</span> <span class="mi">3</span> <span class="o">.</span> <span class="n">dup</span> <span class="n">mul</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">1</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                             <span class="o">-</span><span class="mi">3</span> <span class="mi">3</span> <span class="mi">3</span> <span class="o">.</span> <span class="n">mul</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">1</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                               <span class="o">-</span><span class="mi">3</span> <span class="mi">9</span> <span class="o">.</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">1</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                             <span class="o">-</span><span class="mi">3</span> <span class="mi">9</span> <span class="mi">4</span> <span class="o">.</span> <span class="mi">1</span> <span class="mi">1</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                           <span class="o">-</span><span class="mi">3</span> <span class="mi">9</span> <span class="mi">4</span> <span class="mi">1</span> <span class="o">.</span> <span class="mi">1</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                         <span class="o">-</span><span class="mi">3</span> <span class="mi">9</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mi">1</span> <span class="o">.</span> <span class="o">*</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                           <span class="o">-</span><span class="mi">3</span> <span class="mi">9</span> <span class="mi">4</span> <span class="mi">1</span> <span class="o">.</span> <span class="o">*</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                             <span class="o">-</span><span class="mi">3</span> <span class="mi">9</span> <span class="mi">4</span> <span class="o">.</span> <span class="o">-</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                               <span class="o">-</span><span class="mi">3</span> <span class="mi">5</span> <span class="o">.</span> <span class="n">sqrt</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-                                <span class="o">-</span><span class="mi">3</span> <span class="mf">2.23606797749979</span> <span class="o">.</span> <span class="n">pm</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-              <span class="o">-</span><span class="mf">0.7639320225002102</span> <span class="o">-</span><span class="mf">5.23606797749979</span> <span class="o">.</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-            <span class="o">-</span><span class="mf">0.7639320225002102</span> <span class="o">-</span><span class="mf">5.23606797749979</span> <span class="mi">1</span> <span class="o">.</span> <span class="mi">2</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-          <span class="o">-</span><span class="mf">0.7639320225002102</span> <span class="o">-</span><span class="mf">5.23606797749979</span> <span class="mi">1</span> <span class="mi">2</span> <span class="o">.</span> <span class="o">*</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-            <span class="o">-</span><span class="mf">0.7639320225002102</span> <span class="o">-</span><span class="mf">5.23606797749979</span> <span class="mi">2</span> <span class="o">.</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="n">cons</span> <span class="n">app2</span>
-  <span class="o">-</span><span class="mf">0.7639320225002102</span> <span class="o">-</span><span class="mf">5.23606797749979</span> <span class="mi">2</span> <span class="p">[</span><span class="n">truediv</span><span class="p">]</span> <span class="o">.</span> <span class="n">cons</span> <span class="n">app2</span>
-  <span class="o">-</span><span class="mf">0.7639320225002102</span> <span class="o">-</span><span class="mf">5.23606797749979</span> <span class="p">[</span><span class="mi">2</span> <span class="n">truediv</span><span class="p">]</span> <span class="o">.</span> <span class="n">app2</span>
-                  <span class="p">[</span><span class="o">-</span><span class="mf">0.7639320225002102</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="n">truediv</span><span class="p">]</span> <span class="o">.</span> <span class="n">infra</span> <span class="n">first</span> <span class="p">[</span><span class="o">-</span><span class="mf">5.23606797749979</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="n">truediv</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
-                                <span class="o">-</span><span class="mf">0.7639320225002102</span> <span class="o">.</span> <span class="mi">2</span> <span class="n">truediv</span> <span class="p">[]</span> <span class="n">swaack</span> <span class="n">first</span> <span class="p">[</span><span class="o">-</span><span class="mf">5.23606797749979</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="n">truediv</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
-                              <span class="o">-</span><span class="mf">0.7639320225002102</span> <span class="mi">2</span> <span class="o">.</span> <span class="n">truediv</span> <span class="p">[]</span> <span class="n">swaack</span> <span class="n">first</span> <span class="p">[</span><span class="o">-</span><span class="mf">5.23606797749979</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="n">truediv</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
-                                <span class="o">-</span><span class="mf">0.3819660112501051</span> <span class="o">.</span> <span class="p">[]</span> <span class="n">swaack</span> <span class="n">first</span> <span class="p">[</span><span class="o">-</span><span class="mf">5.23606797749979</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="n">truediv</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
-                             <span class="o">-</span><span class="mf">0.3819660112501051</span> <span class="p">[]</span> <span class="o">.</span> <span class="n">swaack</span> <span class="n">first</span> <span class="p">[</span><span class="o">-</span><span class="mf">5.23606797749979</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="n">truediv</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
-                              <span class="p">[</span><span class="o">-</span><span class="mf">0.3819660112501051</span><span class="p">]</span> <span class="o">.</span> <span class="n">first</span> <span class="p">[</span><span class="o">-</span><span class="mf">5.23606797749979</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="n">truediv</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
-                                <span class="o">-</span><span class="mf">0.3819660112501051</span> <span class="o">.</span> <span class="p">[</span><span class="o">-</span><span class="mf">5.23606797749979</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="n">truediv</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
-            <span class="o">-</span><span class="mf">0.3819660112501051</span> <span class="p">[</span><span class="o">-</span><span class="mf">5.23606797749979</span><span class="p">]</span> <span class="o">.</span> <span class="p">[</span><span class="mi">2</span> <span class="n">truediv</span><span class="p">]</span> <span class="n">infra</span> <span class="n">first</span>
-<span class="o">-</span><span class="mf">0.3819660112501051</span> <span class="p">[</span><span class="o">-</span><span class="mf">5.23606797749979</span><span class="p">]</span> <span class="p">[</span><span class="mi">2</span> <span class="n">truediv</span><span class="p">]</span> <span class="o">.</span> <span class="n">infra</span> <span class="n">first</span>
-                                  <span class="o">-</span><span class="mf">5.23606797749979</span> <span class="o">.</span> <span class="mi">2</span> <span class="n">truediv</span> <span class="p">[</span><span class="o">-</span><span class="mf">0.3819660112501051</span><span class="p">]</span> <span class="n">swaack</span> <span class="n">first</span>
-                                <span class="o">-</span><span class="mf">5.23606797749979</span> <span class="mi">2</span> <span class="o">.</span> <span class="n">truediv</span> <span class="p">[</span><span class="o">-</span><span class="mf">0.3819660112501051</span><span class="p">]</span> <span class="n">swaack</span> <span class="n">first</span>
-                                 <span class="o">-</span><span class="mf">2.618033988749895</span> <span class="o">.</span> <span class="p">[</span><span class="o">-</span><span class="mf">0.3819660112501051</span><span class="p">]</span> <span class="n">swaack</span> <span class="n">first</span>
-           <span class="o">-</span><span class="mf">2.618033988749895</span> <span class="p">[</span><span class="o">-</span><span class="mf">0.3819660112501051</span><span class="p">]</span> <span class="o">.</span> <span class="n">swaack</span> <span class="n">first</span>
-           <span class="o">-</span><span class="mf">0.3819660112501051</span> <span class="p">[</span><span class="o">-</span><span class="mf">2.618033988749895</span><span class="p">]</span> <span class="o">.</span> <span class="n">first</span>
-             <span class="o">-</span><span class="mf">0.3819660112501051</span> <span class="o">-</span><span class="mf">2.618033988749895</span> <span class="o">.</span>
-</pre></div>
-</div>
-</div>
 </div>
 </div>
 
@@ -195,15 +175,14 @@ already.)</p>
   <ul>
 <li><a class="reference internal" href="#">Quadratic formula</a><ul>
 <li><a class="reference internal" href="#write-a-straightforward-program-with-variable-names">Write a straightforward program with variable names.</a><ul>
-<li><a class="reference internal" href="#check-it">Check it.</a></li>
-<li><a class="reference internal" href="#cleanup">Cleanup</a></li>
+<li><a class="reference internal" href="#b"><code class="docutils literal notranslate"><span class="pre">-b</span></code></a></li>
+<li><a class="reference internal" href="#sqrt-b-2-4-a-c"><code class="docutils literal notranslate"><span class="pre">sqrt(b^2</span> <span class="pre">-</span> <span class="pre">4</span> <span class="pre">*</span> <span class="pre">a</span> <span class="pre">*</span> <span class="pre">c)</span></code></a></li>
+<li><a class="reference internal" href="#a"><code class="docutils literal notranslate"><span class="pre">/2a</span></code></a></li>
+<li><a class="reference internal" href="#id1"><code class="docutils literal notranslate"><span class="pre">±</span></code></a></li>
+<li><a class="reference internal" href="#putting-them-together">Putting Them Together</a></li>
 </ul>
 </li>
 <li><a class="reference internal" href="#derive-a-definition">Derive a definition.</a></li>
-<li><a class="reference internal" href="#simplify">Simplify</a><ul>
-<li><a class="reference internal" href="#define-a-native-pm-function">Define a “native” <code class="docutils literal notranslate"><span class="pre">pm</span></code> function.</a></li>
-</ul>
-</li>
 </ul>
 </li>
 </ul>
@@ -212,8 +191,8 @@ already.)</p>
 <ul>
   <li><a href="../index.html">Documentation overview</a><ul>
   <li><a href="index.html">Essays about Programming in Joy</a><ul>
-      <li>Previous: <a href="Newton-Raphson.html" title="previous chapter">Newton’s method</a></li>
-      <li>Next: <a href="Zipper.html" title="next chapter">Traversing Datastructures with Zippers</a></li>
+      <li>Previous: <a href="Developing.html" title="previous chapter">Developing a Program in Joy</a></li>
+      <li>Next: <a href="Replacing.html" title="next chapter">Replacing Functions in the Dictionary</a></li>
   </ul></li>
   </ul></li>
 </ul>

docs/sphinx_docs/_build/html/notebooks/Zipper.html

@@ -16,8 +16,8 @@
     <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
     <link rel="index" title="Index" href="../genindex.html" />
     <link rel="search" title="Search" href="../search.html" />
-    <link rel="next" title="No Updates" href="NoUpdates.html" />
-    <link rel="prev" title="Quadratic formula" href="Quadratic.html" />
+    <link rel="next" title="Type Inference" href="Types.html" />
+    <link rel="prev" title="Newton’s method" href="Newton-Raphson.html" />
    
   <link rel="stylesheet" href="../_static/custom.css" type="text/css" />
   
@@ -326,8 +326,8 @@ i d i d i d d Bingo!
 <ul>
   <li><a href="../index.html">Documentation overview</a><ul>
   <li><a href="index.html">Essays about Programming in Joy</a><ul>
-      <li>Previous: <a href="Quadratic.html" title="previous chapter">Quadratic formula</a></li>
-      <li>Next: <a href="NoUpdates.html" title="next chapter">No Updates</a></li>
+      <li>Previous: <a href="Newton-Raphson.html" title="previous chapter">Newton’s method</a></li>
+      <li>Next: <a href="Types.html" title="next chapter">Type Inference</a></li>
   </ul></li>
   </ul></li>
 </ul>

docs/sphinx_docs/_build/html/notebooks/index.html

@@ -44,12 +44,32 @@
 <li class="toctree-l2"><a class="reference internal" href="Developing.html#the-simplest-program">The Simplest Program</a></li>
 </ul>
 </li>
+<li class="toctree-l1"><a class="reference internal" href="Quadratic.html">Quadratic formula</a><ul>
+<li class="toctree-l2"><a class="reference internal" href="Quadratic.html#write-a-straightforward-program-with-variable-names">Write a straightforward program with variable names.</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Quadratic.html#derive-a-definition">Derive a definition.</a></li>
+</ul>
+</li>
 <li class="toctree-l1"><a class="reference internal" href="Replacing.html">Replacing Functions in the Dictionary</a><ul>
 <li class="toctree-l2"><a class="reference internal" href="Replacing.html#a-long-trace">A long trace</a></li>
 <li class="toctree-l2"><a class="reference internal" href="Replacing.html#replacing-size-with-a-python-version">Replacing <code class="docutils literal notranslate"><span class="pre">size</span></code> with a Python version</a></li>
 <li class="toctree-l2"><a class="reference internal" href="Replacing.html#a-shorter-trace">A shorter trace</a></li>
 </ul>
 </li>
+<li class="toctree-l1"><a class="reference internal" href="Recursion_Combinators.html">Recursive Combinators</a><ul>
+<li class="toctree-l2"><a class="reference internal" href="Recursion_Combinators.html#designing-recursive-functions">Designing Recursive Functions</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Recursion_Combinators.html#primitive-recursive-functions">Primitive Recursive Functions</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Recursion_Combinators.html#hylomorphism">Hylomorphism</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Recursion_Combinators.html#hylomorphism-in-joy">Hylomorphism in Joy</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Recursion_Combinators.html#derivation-of-hylomorphism-combinator">Derivation of <code class="docutils literal notranslate"><span class="pre">hylomorphism</span></code> combinator</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Recursion_Combinators.html#four-specializations">Four Specializations</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Recursion_Combinators.html#anamorphism">Anamorphism</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Recursion_Combinators.html#catamorphism">Catamorphism</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Recursion_Combinators.html#example-factorial-function">Example: Factorial Function</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Recursion_Combinators.html#example-tails">Example: <code class="docutils literal notranslate"><span class="pre">tails</span></code></a></li>
+<li class="toctree-l2"><a class="reference internal" href="Recursion_Combinators.html#conclusion-patterns-of-recursion">Conclusion: Patterns of Recursion</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Recursion_Combinators.html#appendix-fun-with-symbols">Appendix: Fun with Symbols</a></li>
+</ul>
+</li>
 <li class="toctree-l1"><a class="reference internal" href="Ordered_Binary_Trees.html">Treating Trees I: Ordered Binary Trees</a><ul>
 <li class="toctree-l2"><a class="reference internal" href="Ordered_Binary_Trees.html#adding-nodes-to-the-tree">Adding Nodes to the Tree</a></li>
 <li class="toctree-l2"><a class="reference internal" href="Ordered_Binary_Trees.html#interlude-cmp-combinator">Interlude: <code class="docutils literal notranslate"><span class="pre">cmp</span></code> combinator</a></li>
@@ -89,12 +109,6 @@
 <li class="toctree-l2"><a class="reference internal" href="Newton-Raphson.html#finding-consecutive-approximations-within-a-tolerance">Finding Consecutive Approximations within a Tolerance</a></li>
 </ul>
 </li>
-<li class="toctree-l1"><a class="reference internal" href="Quadratic.html">Quadratic formula</a><ul>
-<li class="toctree-l2"><a class="reference internal" href="Quadratic.html#write-a-straightforward-program-with-variable-names">Write a straightforward program with variable names.</a></li>
-<li class="toctree-l2"><a class="reference internal" href="Quadratic.html#derive-a-definition">Derive a definition.</a></li>
-<li class="toctree-l2"><a class="reference internal" href="Quadratic.html#simplify">Simplify</a></li>
-</ul>
-</li>
 <li class="toctree-l1"><a class="reference internal" href="Zipper.html">Traversing Datastructures with Zippers</a><ul>
 <li class="toctree-l2"><a class="reference internal" href="Zipper.html#trees">Trees</a></li>
 <li class="toctree-l2"><a class="reference internal" href="Zipper.html#zipper-in-joy">Zipper in Joy</a></li>
@@ -104,6 +118,20 @@
 <li class="toctree-l2"><a class="reference internal" href="Zipper.html#determining-the-right-path-for-an-item-in-a-tree">Determining the right “path” for an item in a tree.</a></li>
 </ul>
 </li>
+<li class="toctree-l1"><a class="reference internal" href="Types.html">Type Inference</a><ul>
+<li class="toctree-l2"><a class="reference internal" href="Types.html#poial-s-rules">Pöial’s Rules</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Types.html#examples">Examples</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Types.html#implementation">Implementation</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Types.html#compiling">Compiling</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Types.html#types-and-subtypes-of-arguments">Types and Subtypes of Arguments</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Types.html#functions-that-use-the-stack">Functions that use the Stack</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Types.html#sets-of-stack-effects">Sets of Stack Effects</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Types.html#concat"><code class="docutils literal notranslate"><span class="pre">concat</span></code></a></li>
+<li class="toctree-l2"><a class="reference internal" href="Types.html#typing-combinators">Typing Combinators</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Types.html#abstract-interpretation">Abstract Interpretation</a></li>
+<li class="toctree-l2"><a class="reference internal" href="Types.html#something-else">Something else…</a></li>
+</ul>
+</li>
 <li class="toctree-l1"><a class="reference internal" href="NoUpdates.html">No Updates</a></li>
 <li class="toctree-l1"><a class="reference internal" href="Categorical.html">Categorical Programming</a></li>
 </ul>

docs/sphinx_docs/_build/html/stack.html

@@ -80,6 +80,31 @@ iterable and another to iterate through a stack and yield its items
 one-by-one in order.  There are also two functions to generate string representations
 of stacks.  They only differ in that one prints the terms in stack from left-to-right while the other prints from right-to-left.  In both functions <em>internal stacks</em> are
 printed left-to-right.  These functions are written to support <a class="reference internal" href="pretty.html"><span class="doc">Tracing Joy Execution</span></a>.</p>
+<dl class="function">
+<dt id="joy.utils.stack.concat">
+<code class="descclassname">joy.utils.stack.</code><code class="descname">concat</code><span class="sig-paren">(</span><em>quote</em>, <em>expression</em><span class="sig-paren">)</span><a class="reference internal" href="_modules/joy/utils/stack.html#concat"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#joy.utils.stack.concat" title="Permalink to this definition">¶</a></dt>
+<dd><p>Concatinate quote onto expression.</p>
+<p>In joy [1 2] [3 4] would become [1 2 3 4].</p>
+<table class="docutils field-list" frame="void" rules="none">
+<col class="field-name" />
+<col class="field-body" />
+<tbody valign="top">
+<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
+<li><strong>quote</strong> (<em>stack</em>) – A stack.</li>
+<li><strong>expression</strong> (<em>stack</em>) – A stack.</li>
+</ul>
+</td>
+</tr>
+<tr class="field-even field"><th class="field-name">Raises:</th><td class="field-body"><p class="first"><strong>RuntimeError</strong> – if quote is larger than sys.getrecursionlimit().</p>
+</td>
+</tr>
+<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">stack</p>
+</td>
+</tr>
+</tbody>
+</table>
+</dd></dl>
+
 <dl class="function">
 <dt id="joy.utils.stack.expression_to_string">
 <code class="descclassname">joy.utils.stack.</code><code class="descname">expression_to_string</code><span class="sig-paren">(</span><em>expression</em><span class="sig-paren">)</span><a class="reference internal" href="_modules/joy/utils/stack.html#expression_to_string"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#joy.utils.stack.expression_to_string" title="Permalink to this definition">¶</a></dt>
@@ -168,31 +193,6 @@ won’t work because <code class="docutils literal notranslate"><span class="pre
 </table>
 </dd></dl>
 
-<dl class="function">
-<dt id="joy.utils.stack.pushback">
-<code class="descclassname">joy.utils.stack.</code><code class="descname">pushback</code><span class="sig-paren">(</span><em>quote</em>, <em>expression</em><span class="sig-paren">)</span><a class="reference internal" href="_modules/joy/utils/stack.html#pushback"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#joy.utils.stack.pushback" title="Permalink to this definition">¶</a></dt>
-<dd><p>Concatinate quote onto expression.</p>
-<p>In joy [1 2] [3 4] would become [1 2 3 4].</p>
-<table class="docutils field-list" frame="void" rules="none">
-<col class="field-name" />
-<col class="field-body" />
-<tbody valign="top">
-<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
-<li><strong>quote</strong> (<em>stack</em>) – A stack.</li>
-<li><strong>expression</strong> (<em>stack</em>) – A stack.</li>
-</ul>
-</td>
-</tr>
-<tr class="field-even field"><th class="field-name">Raises:</th><td class="field-body"><p class="first"><strong>RuntimeError</strong> – if quote is larger than sys.getrecursionlimit().</p>
-</td>
-</tr>
-<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">stack</p>
-</td>
-</tr>
-</tbody>
-</table>
-</dd></dl>
-
 <dl class="function">
 <dt id="joy.utils.stack.stack_to_string">
 <code class="descclassname">joy.utils.stack.</code><code class="descname">stack_to_string</code><span class="sig-paren">(</span><em>stack</em><span class="sig-paren">)</span><a class="reference internal" href="_modules/joy/utils/stack.html#stack_to_string"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#joy.utils.stack.stack_to_string" title="Permalink to this definition">¶</a></dt>