Extra logging and another lil test.

joy/utils/polytypes.py

@@ -153,6 +153,22 @@ class CombinatorJoyType(FunctionJoyType):
         return new_f[0][1]
 
 
+def _log_uni(U):
+  def inner(u, v, s=None):
+    _log.info(
+      '%3i %s U %s   w/ %s',
+      len(inspect_stack()), u, v, s,
+      )
+    res = U(u, v, s)
+    _log.info(
+      '%3i %s U %s   w/ %s => %s',
+      len(inspect_stack()), u, v, s, res,
+      )
+    return res
+  return inner
+
+
+@_log_uni
 def unify(u, v, s=None):
     '''
     Return a tuple of substitution dicts representing unifiers for u and v.

test/test_type_inference.py

@@ -174,6 +174,12 @@ class TestYin(TestMixin, unittest.TestCase):
     # ([...1] -- [a2 ...1] [...3] a1)
     self.assertEqualTypeStructure(infer(*expression), [f])
 
+  def test_stack_dup_ccons(self):
+    expression = stack, dup, ccons
+    f = ((a1, s1), ((a1, ((a1, s1), (a1, s1))), s1))
+    # (... a1 -- ... [a1 [a1 ...] a1 ...])
+    self.assertEqualTypeStructure(infer(*expression), [f])
+
 ##  def test_(self):
 ##    expression = pop, swap, rolldown, rest, rest, cons, cons
 ##    f =