Use rec so functions can refer to themselves in their bodies.

Code like the following kind is legal in Python:

```python
def recursive(a): return recursive
```

This implies that function and class definitions need to use the Core
`rec` construct so that their bodies have an appropriate entry in the scope.

semantic-python/src/Language/Python/Core.hs

@@ -206,7 +206,8 @@ instance Compile Py.ClassDefinition where
           pure (typefn $$ Core.string (coerce n) $$ object $$ contents)
 
     body <- compile pybody buildTypeCall next
-    let assignClass = Name.named' n :<- body
+    let coreName = Name.named' n
+    let assignClass = coreName :<- (rec coreName body)
     let continuing = fmap (locate it . (assignClass >>>=))
     continuing (local (def n) (cc next))
 
@@ -277,7 +278,7 @@ instance Compile Py.FunctionDefinition where
       parameters' <- traverse param parameters
       body' <- compile body pure next
       -- Build a lambda.
-      let located = locate it (lams parameters' body')
+      let located = locate it (rec (Name.named' (Name name)) (lams parameters' body'))
       -- Give it a name (below), then augment the current continuation
       -- with the new name (with 'def'), so that calling contexts know
       -- that we have built an exportable definition.

semantic-python/test/fixtures/2-01-return-statement.py

@@ -1,3 +1,3 @@
-# CHECK-TREE: { foo <- (\a -> a); #record { foo: foo } }
+# CHECK-TREE: { foo <- rec foo = \a -> a; #record { foo: foo } }
 def foo(a):
     return a

semantic-python/test/fixtures/2-02-return-doesnt-translate.py

@@ -1,4 +1,4 @@
-# CHECK-TREE: { foo <- (\a -> a); #record { foo: foo } }
+# CHECK-TREE: { foo <- rec foo = (\a -> a); #record { foo: foo } }
 
 def foo(a):
     return a

semantic-python/test/fixtures/2-03-return-in-if-statement.py

@@ -1,4 +1,4 @@
-# CHECK-TREE: { foo <- \a -> if a then a else #unit; #record { foo: foo } }
+# CHECK-TREE: { foo <- rec foo = \a -> if a then a else #unit; #record { foo: foo } }
 
 def foo(a):
     if a: return a

semantic-python/test/fixtures/2-05-function-call.py

@@ -1,4 +1,4 @@
-# CHECK-TREE: { const <- \x -> \y -> x; y <- const #true #true; z <- const #false #false; #record { const: const, y : y, z: z, }}
+# CHECK-TREE: { const <- rec const = \x -> \y -> x; y <- const #true #true; z <- const #false #false; #record { const: const, y : y, z: z, }}
 def const(x, y): return x
 y = const(True, True)
 z = const(False, False)

semantic-python/test/fixtures/2-06-nested-function-definition.py

@@ -1,4 +1,4 @@
-# CHECK-TREE: { const <- \a -> \b -> { identity <- \x -> x; identity a }; #record{ const: const }}
+# CHECK-TREE: { const <- rec const = \a -> \b -> { identity <- rec identity = \x -> x; identity a }; #record{ const: const }}
 
 def const(a, b):
     def identity(x):

semantic-python/test/fixtures/2-08-function-decorator.py

@@ -1,4 +1,4 @@
-# CHECK-TREE: { passthru <- \x -> x; decorated <- \x -> x; decorated = passthru(decorated); #record { passthru: passthru, decorated: decorated }}
+# CHECK-TREE: { passthru <- rec passthru = \x -> x; decorated <- rec decorated = \x -> x; decorated = passthru(decorated); #record { passthru: passthru, decorated: decorated }}
 def passthru(x):
     return x
 

semantic-python/test/fixtures/3-01-empty-class-definition.py

@@ -1,3 +1,3 @@
-# CHECK-TREE: { Foo <- __semantic_prelude.type "Foo" __semantic_prelude.object #record {}; #record { Foo: Foo }}
+# CHECK-TREE: { Foo <- rec Foo = __semantic_prelude.type "Foo" __semantic_prelude.object #record {}; #record { Foo: Foo }}
 class Foo():
     pass

semantic-python/test/fixtures/3-02-defining-instance-method.py

@@ -1,4 +1,4 @@
-# CHECK-TREE: { Foo <- { identity <- \self -> \x -> x; __semantic_prelude.type "Foo" __semantic_prelude.object #record { identity: identity } }; #record { Foo: Foo } }
+# CHECK-TREE: { Foo <- rec Foo = { identity <- rec identity = \self -> \x -> x; __semantic_prelude.type "Foo" __semantic_prelude.object #record { identity: identity } }; #record { Foo: Foo } }
 
 class Foo():
     def identity(self, x):

semantic-python/test/fixtures/3-03-functions-know-their-own-names.py

@@ -0,0 +1,4 @@
+# CHECK-TREE: { recursive <- rec recursive = \a -> recursive; #record { recursive: recursive }}
+def recursive(a): return recursive
+
+# this should scope correctly in the graph but it doesn't seem to yet