From 576aee6c99f9d06a4faa44f4cef17b68672f07d0 Mon Sep 17 00:00:00 2001
From: Ben Gamari <ben@smart-cactus.org>
Date: Mon, 14 Aug 2017 20:45:14 -0400
Subject: [PATCH] gray: AMP compatibility

Reviewers: O26 nofib, michalt

Reviewed By: O26 nofib, michalt

Subscribers: michalt

Differential Revision: https://phabricator.haskell.org/D3730
---
 parallel/gray/Eval.hs | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/parallel/gray/Eval.hs b/parallel/gray/Eval.hs
index 367942b..29c2bac 100644
--- a/parallel/gray/Eval.hs
+++ b/parallel/gray/Eval.hs
@@ -14,6 +14,7 @@ import Data
 import Parse (rayParse, rayParseF)
 
 import Control.Parallel
+import Control.Monad (ap)
 
 class Monad m => MonadEval m where
   doOp :: PrimOp -> GMLOp -> Stack -> m Stack
@@ -24,6 +25,13 @@ class Monad m => MonadEval m where
 
 newtype Pure a = Pure a deriving Show
 
+instance Functor Pure where
+    fmap f (Pure x) = Pure (f x)
+
+instance Applicative Pure where
+    pure = Pure
+    Pure f <*> Pure x = Pure (f x)
+
 instance Monad Pure where
     Pure x >>= k = k x
     return       = Pure
@@ -293,11 +301,18 @@ newtype Abs a   = Abs { runAbs :: Int -> AbsState a }
 data AbsState a = AbsState a !Int
                 | AbsFail String
 
+instance Functor Abs where
+    fmap f = (pure f <*>)
+
+instance Applicative Abs where
+    pure x = Abs (\ n -> AbsState x n)
+    (<*>)  = ap
+
 instance Monad Abs where
     (Abs fn) >>= k = Abs (\ s -> case fn s of
 			           AbsState r s' -> runAbs (k r) s'
                                    AbsFail m     -> AbsFail m)
-    return x     = Abs (\ n -> AbsState x n)
+    return       = pure
     fail s       = Abs (\ n -> AbsFail s)
 
 instance MonadEval Abs where
-- 
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