Dang it...

bigjoyints/big.py

@@ -171,8 +171,7 @@ class BigInt:
         for a, b in Z:
             carry, digit = a.sub_with_carry(b, carry)
             out.append(digit)
-        if carry:
-            out.append(one)
+        assert not carry  # a >= b, eh?
         result = BigInt()
         result.sign = self.sign
         result.digits = out

implementations/Python/bigints.joy

@@ -0,0 +1,20 @@
+[base 2147483648] inscribe
+[valid_digit [0 >] [base <] &&] inscribe
+[_add_p [bool not] ii &] inscribe
+[_add_then pop swap [] [1 swons] branch] inscribe
+[_add_rec_pred [bool] ii &] inscribe
+[bool_to_int [0] [1] branch] inscribe
+[_add-with-carry0 [bool_to_int] dipd + +] inscribe
+[_add-with-carry1 base [mod] [>=] clop] inscribe
+[add-with-carry _add-with-carry0 _add-with-carry1] inscribe
+[uncons-two [uncons] ii swapd] inscribe
+[ditch-empty-list [bool] [popd] [pop] ifte] inscribe
+[add-carry-to-digits [pop not] [popd] [[bool not] [1 swons popd]] [[0 swap uncons [add-with-carry] dip] swoncat ifte] genrec] inscribe
+[THEN0 uncons-two [add-with-carry] dipd] inscribe
+[THEN1 i cons] inscribe
+[ELSE ditch-empty-list add-carry-to-digits] inscribe
+[_add_R0 [_add_rec_pred] [THEN0]] inscribe
+[_add_R1 [THEN1] cons concat [ELSE] ifte cons] inscribe
+[add_digits [_add_p] [_add_then] [_add_R0] [_add_R1] genrec cons ] inscribe
+clear false base -- unit dup concat dup concat [1]
+[add_digits] trace

implementations/Python/joy.py

@@ -1369,18 +1369,24 @@ def trace(stack, expr, dictionary):
     history = []
     append = history.append
     local_expr = push_quote(quote)
-    while local_expr:
-        append((stack, local_expr))
-        term, local_expr = next_term(local_expr)
-        if isinstance(term, Symbol):
-            try:
-                func = dictionary[term]
-            except KeyError:
-                print(trace_to_string(history))
-                raise UnknownSymbolError(term) from None
-            stack, local_expr, dictionary = func(stack, local_expr, dictionary)
-        else:
-            stack = term, stack
+    try:
+        while local_expr:
+            if len(history) > 1000:
+                break
+            append((stack, local_expr))
+            term, local_expr = next_term(local_expr)
+            if isinstance(term, Symbol):
+                try:
+                    func = dictionary[term]
+                except KeyError:
+                    print(trace_to_string(history))
+                    raise UnknownSymbolError(term) from None
+                stack, local_expr, dictionary = func(stack, local_expr, dictionary)
+            else:
+                stack = term, stack
+    except:
+        print(trace_to_string(history))
+        raise
     append((stack, local_expr))
     print(trace_to_string(history))
     return stack, expr, dictionary