[project @ 2005-01-19 22:33:32 by ralf]

[ghc-base.git] / Data / Array.hs

diff --git a/Data/Array.hs b/Data/Array.hs
index e8e8c76..cd41677 100644 (file)
--- a/Data/Array.hs
+++ b/Data/Array.hs
@@ -58,8 +58,10 @@ module  Data.Array
 import Data.Ix
 
 #ifdef __GLASGOW_HASKELL__
-import GHC.Arr         -- Most of the hard work is done here
-import GHC.Err         ( undefined )
+import GHC.Arr                 -- Most of the hard work is done here
+import Data.Generics.Basics     -- To provide a Data instance
+import Data.Generics.Instances  -- To provide a Data instance
+import GHC.Err ( error )        -- Needed for Data instance
 #endif
 
 #ifdef __HUGS__
@@ -79,6 +81,20 @@ import Data.Typeable
 INSTANCE_TYPEABLE2(Array,arrayTc,"Array")
 #endif
 
+#ifdef __GLASGOW_HASKELL__
+
+-- This instance preserves data abstraction at the cost of inefficiency.
+-- We omit reflection services for the sake of data abstraction.
+
+instance (Typeable a, Data b, Ix a) => Data (Array a b)
+ where
+  gfoldl f z a = z (listArray (bounds a)) `f` (elems a)
+  toConstr _   = error "toConstr"
+  gunfold _ _  = error "gunfold"
+  dataTypeOf _ = mkNorepType "Data.Array.Array"
+
+#endif
+
 {- $intro
 Haskell provides indexable /arrays/, which may be thought of as functions
 whose domains are isomorphic to contiguous subsets of the integers.