From c01a362a8cf718ff2ed317846022a3e8fa26c420 Mon Sep 17 00:00:00 2001
From: "lennart@augustsson.net" <unknown>
Date: Thu, 21 Dec 2006 21:05:32 +0000
Subject: [PATCH] Add IsString class for overloaded string literals.

---
 Foreign/Marshal/Pool.hs |    2 +-
 GHC/Base.lhs            |    8 ++++++++
 Prelude.hs              |    3 +++
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/Foreign/Marshal/Pool.hs b/Foreign/Marshal/Pool.hs
index a2a73ac..3f7e2d5 100644
--- a/Foreign/Marshal/Pool.hs
+++ b/Foreign/Marshal/Pool.hs
@@ -45,7 +45,7 @@ module Foreign.Marshal.Pool (
 ) where
 
 #ifdef __GLASGOW_HASKELL__
-import GHC.Base              ( Int, Monad(..), (.), not )
+import GHC.Base              ( Int, Monad(..), IsString(..), (.), not )
 import GHC.Err               ( undefined )
 import GHC.Exception         ( block, unblock, throw, catchException )
 import GHC.IOBase            ( IO, IORef, newIORef, readIORef, writeIORef, )
diff --git a/GHC/Base.lhs b/GHC/Base.lhs
index 4fc09a6..5522e23 100644
--- a/GHC/Base.lhs
+++ b/GHC/Base.lhs
@@ -496,6 +496,14 @@ otherwise		:: Bool
 otherwise 		=  True
 \end{code}
 
+\begin{code}
+class IsString a where
+    fromString :: String -> a
+
+instance IsString [Char] where
+    fromString xs = xs
+\end{code}
+
 
 %*********************************************************
 %*							*
diff --git a/Prelude.hs b/Prelude.hs
index 840c2ca..cae9c25 100644
--- a/Prelude.hs
+++ b/Prelude.hs
@@ -80,6 +80,9 @@ module Prelude (
     Functor(fmap),
     mapM, mapM_, sequence, sequence_, (=<<),
 
+    -- ** String class
+    IsString(fromString),
+
     -- ** Miscellaneous functions
     id, const, (.), flip, ($), until,
     asTypeOf, error, undefined,
-- 
1.7.10.4