From de4c3e5f8af27d07ef5ad1532e4e0cb906361a56 Mon Sep 17 00:00:00 2001
From: Patrick Thomson <patrickt@github.com>
Date: Fri, 16 Mar 2018 17:07:53 -0400
Subject: [PATCH] Take a stab at typechecking.

---
 src/Control/Abstract/Addressable.hs | 1 +
 src/Control/Abstract/Value.hs       | 3 +++
 src/Data/Abstract/Type.hs           | 1 +
 3 files changed, 5 insertions(+)

diff --git a/src/Control/Abstract/Addressable.hs b/src/Control/Abstract/Addressable.hs
index 47171c135..a2919363d 100644
--- a/src/Control/Abstract/Addressable.hs
+++ b/src/Control/Abstract/Addressable.hs
@@ -48,6 +48,7 @@ letrec name body = do
 instance (MonadFail m, LocationFor value ~ Precise, MonadHeap value m) => MonadAddressable Precise value m where
   deref = derefWith (maybeM uninitializedAddress . unLatest)
   alloc _ = do
+    -- Compute the next available address in the heap, then write an empty value into it.
     addr <- fmap (Address . Precise . heapSize) getHeap
     addr <$ modifyHeap (heapInit addr mempty)
 
diff --git a/src/Control/Abstract/Value.hs b/src/Control/Abstract/Value.hs
index e61384242..0c7b90914 100644
--- a/src/Control/Abstract/Value.hs
+++ b/src/Control/Abstract/Value.hs
@@ -261,6 +261,9 @@ instance (Alternative m, MonadEnvironment Type m, MonadFail m, MonadFresh m, Mon
   rational _ = pure Type.Rational
   multiple   = pure . Type.Product
   array      = pure . Type.Array
+  klass _ _  = pure Object
+
+  objectEnvironment _ = pure mempty
 
   ifthenelse cond if' else' = unify cond Bool *> (if' <|> else')
 
diff --git a/src/Data/Abstract/Type.hs b/src/Data/Abstract/Type.hs
index 15fa96dbe..8da343b44 100644
--- a/src/Data/Abstract/Type.hs
+++ b/src/Data/Abstract/Type.hs
@@ -20,6 +20,7 @@ data Type
   | Var TName      -- ^ A type variable.
   | Product [Type] -- ^ N-ary products.
   | Array [Type]   -- ^ Arrays. Note that this is heterogenous.
+  | Object         -- ^ Objects. Once we have some notion of inheritance we'll need to store a superclass.
   deriving (Eq, Ord, Show)
 
 -- TODO: À la carte representation of types.