Read instances

Author: knrafto

Data/HashMap/Base.hs

@@ -93,6 +93,7 @@ import Data.Traversable (Traversable(..))
 import Data.Word (Word)
 import GHC.Exts ((==#), build, reallyUnsafePtrEquality#)
 import Prelude hiding (filter, foldr, lookup, map, null, pred)
+import Text.Read hiding (step)
 
 import qualified Data.HashMap.Array as A
 import qualified Data.Hashable as H
@@ -173,6 +174,14 @@ type Hash   = Word
 type Bitmap = Word
 type Shift  = Int
 
+instance (Eq k, Hashable k, Read k, Read e) => Read (HashMap k e) where
+    readPrec = parens $ prec 10 $ do
+      Ident "fromList" <- lexP
+      xs <- readPrec
+      return (fromList xs)
+
+    readListPrec = readListPrecDefault
+
 instance (Show k, Show v) => Show (HashMap k v) where
     showsPrec d m = showParen (d > 10) $
       showString "fromList " . shows (toList m)

Data/HashSet.hs

@@ -73,6 +73,7 @@ import qualified Data.Foldable as Foldable
 import qualified Data.HashMap.Lazy as H
 import qualified Data.List as List
 import Data.Typeable (Typeable)
+import Text.Read
 
 #if __GLASGOW_HASKELL__ >= 708
 import qualified GHC.Exts as Exts
@@ -103,6 +104,14 @@ instance (Hashable a, Eq a) => Monoid (HashSet a) where
     mappend = union
     {-# INLINE mappend #-}
 
+instance (Eq a, Hashable a, Read a) => Read (HashSet a) where
+    readPrec = parens $ prec 10 $ do
+      Ident "fromList" <- lexP
+      xs <- readPrec
+      return (fromList xs)
+
+    readListPrec = readListPrecDefault
+
 instance (Show a) => Show (HashSet a) where
     showsPrec d m = showParen (d > 10) $
       showString "fromList " . shows (toList m)