fixed for loop unification

hm-inference/ast_visitor.py

@@ -172,7 +172,7 @@ class Visitor(ast.NodeVisitor):
     def visit_For(self, node):
         self.visit(node.target)
         self.visit(node.iter)
-        ty = node.iter.type
+        ty = node.iter.type.find()
         if isinstance(ty, TVar):
             # we currently only support iterator over lists
             ty.type = ty.type.unifier(TVarType.LIST)

hm-inference/nac3_types.py

@@ -122,14 +122,8 @@ class TVar(Type):
         elif isinstance(y, TVar):
             # check fields
             if isinstance(x, TVirtual):
-                if y.type not in [TVarType.UNDETERMINED, TVarType.RECORD]:
-                    raise UnificationError(f'Cannot unify {y} with {x}')
-                for k, v in y.fields.items():
-                    if k not in x.obj.fields:
-                        raise UnificationError(
-                            f'Cannot unify {y} with {x}')
-                    u = x.obj.fields[k]
-                    v.unify(u)
+                obj = x.obj.find()
+                self.unify(obj)
             elif isinstance(x, TObj):
                 if y.type not in [TVarType.UNDETERMINED, TVarType.RECORD]:
                     raise UnificationError(f'Cannot unify {y} with {x}')
@@ -397,6 +391,8 @@ class TVirtual(Type):
         o = other.find()
         if isinstance(o, TVirtual):
             self.obj.unify(o.obj)
+        elif isinstance(o, TVar):
+            o.unify(self)
         else:
             raise UnificationError(f'Cannot unify {self} with {o}')
 

hm-inference/test.py

@@ -5,13 +5,14 @@ from nac3_types import *
 from primitives import *
 
 src = """
-a = virtual(bar)
-b = test_virtual(a)
 
-a = virtual(foo)
-b = test_virtual(a)
+a = [
+    virtual(bar),
+    virtual(foo),
+]
 
-c = virtual(foo, Foo)
+for x in a:
+    test_virtual(x)
 """
 
 foo = TObj('Foo', {