From 3407b4d273624ea5976c57f3582b4d5483f2ffb2 Mon Sep 17 00:00:00 2001
From: Patrick Thomson <patrickt@github.com>
Date: Tue, 17 Dec 2019 13:14:17 -0500
Subject: [PATCH 1/5] Introduce helper for preluded definitions.

---
 semantic-python/src/Language/Python/Core.hs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/semantic-python/src/Language/Python/Core.hs b/semantic-python/src/Language/Python/Core.hs
index f3ca48783..37d0120d9 100644
--- a/semantic-python/src/Language/Python/Core.hs
+++ b/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.

From 228e3470e9107809ec8d4e32256f1c02f70b985c Mon Sep 17 00:00:00 2001
From: Patrick Thomson <patrickt@github.com>
Date: Tue, 17 Dec 2019 13:14:30 -0500
Subject: [PATCH 2/5] Use preluded helper.

---
 semantic-python/src/Language/Python/Core.hs | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/semantic-python/src/Language/Python/Core.hs b/semantic-python/src/Language/Python/Core.hs
index 37d0120d9..1035ac406 100644
--- a/semantic-python/src/Language/Python/Core.hs
+++ b/semantic-python/src/Language/Python/Core.hs
@@ -199,8 +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)
 
@@ -346,8 +346,8 @@ 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
@@ -387,7 +387,7 @@ 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

From e7c7910760c5302ac5e7ae20f1e297b1cb79c0b6 Mon Sep 17 00:00:00 2001
From: Patrick Thomson <patrickt@github.com>
Date: Tue, 17 Dec 2019 13:22:36 -0500
Subject: [PATCH 3/5] Add provisional __not__ definition.

---
 semantic-python/src/Prelude.score | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/semantic-python/src/Prelude.score b/semantic-python/src/Prelude.score
index 775f96b3a..53130556e 100644
--- a/semantic-python/src/Prelude.score
+++ b/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}

From 9d0afb4f0a56fc129b1f5099c0a1356b8695499c Mon Sep 17 00:00:00 2001
From: Patrick Thomson <patrickt@github.com>
Date: Tue, 17 Dec 2019 13:25:59 -0500
Subject: [PATCH 4/5] Compile not statements.

---
 semantic-python/src/Language/Python/Core.hs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/semantic-python/src/Language/Python/Core.hs b/semantic-python/src/Language/Python/Core.hs
index 1035ac406..556cd03ce 100644
--- a/semantic-python/src/Language/Python/Core.hs
+++ b/semantic-python/src/Language/Python/Core.hs
@@ -350,7 +350,11 @@ instance Compile Py.None where
   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

From 74183dba8c14ef847ad5f6c921b2b31e8d839d8e Mon Sep 17 00:00:00 2001
From: Patrick Thomson <patrickt@github.com>
Date: Tue, 17 Dec 2019 13:26:17 -0500
Subject: [PATCH 5/5] Add a test.

---
 semantic-python/test/fixtures/4-03-not-expression.py | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 semantic-python/test/fixtures/4-03-not-expression.py

diff --git a/semantic-python/test/fixtures/4-03-not-expression.py b/semantic-python/test/fixtures/4-03-not-expression.py
new file mode 100644
index 000000000..47c903f41
--- /dev/null
+++ b/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