165 lines
7.1 KiB
ReStructuredText
165 lines
7.1 KiB
ReStructuredText
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Preamble
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~~~~~~~~
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.. code:: ipython2
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from notebook_preamble import D, J, V
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A long trace
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~~~~~~~~~~~~
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.. code:: ipython2
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V('[23 18] average')
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.. parsed-literal::
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. [23 18] average
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[23 18] . average
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[23 18] . [sum 1.0 *] [size] cleave /
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[23 18] [sum 1.0 *] . [size] cleave /
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[23 18] [sum 1.0 *] [size] . cleave /
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[23 18] [sum 1.0 *] [size] . [i] app2 [popd] dip /
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[23 18] [sum 1.0 *] [size] [i] . app2 [popd] dip /
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[23 18] [[sum 1.0 *] [23 18]] [i] . infra first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] [sum 1.0 *] . i [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] . sum 1.0 * [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41 . 1.0 * [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41 1.0 . * [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41.0 . [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41.0 [[23 18]] . swaack first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] [41.0] . first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] 41.0 . [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] 41.0 [[size] [23 18]] . [i] infra first [popd] dip /
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[23 18] 41.0 [[size] [23 18]] [i] . infra first [popd] dip /
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[23 18] [size] . i [41.0 [23 18]] swaack first [popd] dip /
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[23 18] . size [41.0 [23 18]] swaack first [popd] dip /
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[23 18] . 0 swap [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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[23 18] 0 . swap [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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0 [23 18] . [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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0 [23 18] [pop ++] . step [41.0 [23 18]] swaack first [popd] dip /
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0 23 [pop ++] . i [18] [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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0 23 . pop ++ [18] [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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0 . ++ [18] [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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1 . [18] [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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1 [18] . [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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1 [18] [pop ++] . step [41.0 [23 18]] swaack first [popd] dip /
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1 18 [pop ++] . i [41.0 [23 18]] swaack first [popd] dip /
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1 18 . pop ++ [41.0 [23 18]] swaack first [popd] dip /
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1 . ++ [41.0 [23 18]] swaack first [popd] dip /
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2 . [41.0 [23 18]] swaack first [popd] dip /
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2 [41.0 [23 18]] . swaack first [popd] dip /
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[23 18] 41.0 [2] . first [popd] dip /
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[23 18] 41.0 2 . [popd] dip /
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[23 18] 41.0 2 [popd] . dip /
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[23 18] 41.0 . popd 2 /
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41.0 . 2 /
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41.0 2 . /
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20.5 .
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Replacing ``sum`` and ``size`` with "compiled" versions.
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Both ``sum`` and ``size`` are
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`catamorphisms <https://en.wikipedia.org/wiki/Catamorphism>`__, they
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each convert a sequence to a single value.
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.. code:: ipython2
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J('[sum] help')
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.. parsed-literal::
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Given a quoted sequence of numbers return the sum.
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sum == 0 swap [+] step
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.. code:: ipython2
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J('[size] help')
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.. parsed-literal::
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0 swap [pop ++] step
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We can use "compiled" versions (they're not really compiled in this
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case, they're hand-written in Python) to speed up evaluation and make
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the trace more readable. The ``sum`` function is already in the library.
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It gets shadowed by the definition version above during
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``initialize()``.
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.. code:: ipython2
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from joy.library import SimpleFunctionWrapper, primitives
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from joy.utils.stack import iter_stack
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@SimpleFunctionWrapper
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def size(stack):
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'''Return the size of the sequence on the stack.'''
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sequence, stack = stack
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n = 0
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for _ in iter_stack(sequence):
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n += 1
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return n, stack
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sum_ = next(p for p in primitives if p.name == 'sum')
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Now we replace them old versions in the dictionary with the new versions
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and re-evaluate the expression.
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.. code:: ipython2
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old_sum, D['sum'] = D['sum'], sum_
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old_size, D['size'] = D['size'], size
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You can see that ``size`` and ``sum`` now execute in a single step.
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.. code:: ipython2
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V('[23 18] average')
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.. parsed-literal::
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. [23 18] average
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[23 18] . average
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[23 18] . [sum 1.0 *] [size] cleave /
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[23 18] [sum 1.0 *] . [size] cleave /
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[23 18] [sum 1.0 *] [size] . cleave /
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[23 18] [sum 1.0 *] [size] . [i] app2 [popd] dip /
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[23 18] [sum 1.0 *] [size] [i] . app2 [popd] dip /
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[23 18] [[sum 1.0 *] [23 18]] [i] . infra first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] [sum 1.0 *] . i [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] . sum 1.0 * [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41 . 1.0 * [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41 1.0 . * [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41.0 . [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41.0 [[23 18]] . swaack first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] [41.0] . first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] 41.0 . [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] 41.0 [[size] [23 18]] . [i] infra first [popd] dip /
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[23 18] 41.0 [[size] [23 18]] [i] . infra first [popd] dip /
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[23 18] [size] . i [41.0 [23 18]] swaack first [popd] dip /
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[23 18] . size [41.0 [23 18]] swaack first [popd] dip /
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2 . [41.0 [23 18]] swaack first [popd] dip /
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2 [41.0 [23 18]] . swaack first [popd] dip /
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[23 18] 41.0 [2] . first [popd] dip /
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[23 18] 41.0 2 . [popd] dip /
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[23 18] 41.0 2 [popd] . dip /
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[23 18] 41.0 . popd 2 /
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41.0 . 2 /
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41.0 2 . /
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20.5 .
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