Merge pull request #407 from github/not-the-branch-you're-looking-for

Compile `not` statements.

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

@@ -46,6 +46,9 @@ pattern SingleIdentifier name <- Py.ExpressionList
     ]
   }
 
+prelude :: Has Core sig t => [Name] -> t Name
+prelude = foldl' (\a b -> a ... b) (pure "__semantic_prelude")
+
 -- We leave the representation of Core syntax abstract so that it's not
 -- possible for us to 'cheat' by pattern-matching on or eliminating a
 -- compiled term.
@@ -196,8 +199,8 @@ instance Compile Py.ClassDefinition where
           bindings <- asks @Bindings (toList . unBindings)
           let buildName n = (n, pure n)
               contents = record . fmap buildName $ bindings
-              typefn = pure "__semantic_prelude" ... "type"
-              object = pure "__semantic_prelude" ... "object"
+              typefn = prelude ["type"]
+              object = prelude ["object"]
 
           pure (typefn $$ Core.string (coerce n) $$ object $$ contents)
 
@@ -343,11 +346,15 @@ instance Compile Py.Module where
 instance Compile Py.NamedExpression
 
 instance Compile Py.None where
-  -- None is not overridable, and thus always points to the prelude's None.
-  compile _it cc _ = cc (pure "__semantic_prelude" ... "None")
+  -- None is not an lvalue, and thus always points to the prelude's None.
+  compile _it cc _ = cc (prelude ["None"])
 
 instance Compile Py.NonlocalStatement
-instance Compile Py.NotOperator
+
+instance Compile Py.NotOperator where
+  compile _it@Py.NotOperator{ argument } cc next = do
+    val <- compile argument pure next
+    cc (prelude ["not"] $$ val)
 
 instance Compile Py.ParenthesizedExpression where
   compile it@Py.ParenthesizedExpression { extraChildren } cc
@@ -384,7 +391,7 @@ instance Compile Py.String where
 
     if any isNothing contents
       then pure . invariantViolated $ "Couldn't string-desugar " <> show it
-      else let new = pure "__semantic_prelude" ... "str" ... "__slots" ... "__new__"
+      else let new = prelude ["str", "__slots", "__new__"]
            in cc $ locate it (new $$ Core.string (mconcat (catMaybes contents)))
 
 instance Compile Py.Subscript

semantic-python/src/Prelude.score

@@ -10,6 +10,10 @@
 
   str <- type "str" object #record { __new__: \prim -> instance #unit prim #record{} };
 
+  // We will fill in the actual definition of these operators
+  // pending the presence of more eliminators.
+  not <- \val -> if val then #false else #true;
+
   NoneType <- type "None" object #record { __new__: \prim -> instance #unit prim #record{} };
   None <- NoneType.__slots.__new__ #unit;
 
@@ -19,6 +23,7 @@
   #record { type: type
           , object: object
           , str: str
+          , not: not
           , NoneType: NoneType
           , None: None
           , getitem: getitem}

semantic-python/test/fixtures/4-03-not-expression.py

@@ -0,0 +1,2 @@
+# CHECK-TREE: { x <- __semantic_prelude.not #true; #record { x: x }}
+x = not True