\section[Bags]{@Bag@: an unordered collection with duplicates}
\begin{code}
+#ifdef COMPILING_GHC
#include "HsVersions.h"
+#endif
module Bag (
Bag, -- abstract type
emptyBag, unitBag, unionBags, unionManyBags,
- mapBag, -- UNUSED: elemBag,
+ mapBag,
+#ifndef COMPILING_GHC
+ elemBag,
+#endif
filterBag, partitionBag, concatBag, foldBag,
isEmptyBag, consBag, snocBag,
listToBag, bagToList
import Outputable ( interpp'SP )
import Pretty
+#else
+import List(partition)
#endif
data Bag a
emptyBag = EmptyBag
unitBag = UnitBag
-{- UNUSED:
+#ifndef COMPILING_GHC
elemBag :: Eq a => a -> Bag a -> Bool
elemBag x EmptyBag = False
elemBag x (TwoBags b1 b2) = x `elemBag` b1 || x `elemBag` b2
elemBag x (ListBag ys) = any (x ==) ys
elemBag x (ListOfBags bs) = any (x `elemBag`) bs
--}
+#endif
unionManyBags [] = EmptyBag
unionManyBags xs = ListOfBags xs
unionBags b1 b2 = TwoBags b1 b2
consBag :: a -> Bag a -> Bag a
-consBag elt bag = (unitBag elt) `unionBags` bag
snocBag :: Bag a -> a -> Bag a
+
+consBag elt bag = (unitBag elt) `unionBags` bag
snocBag bag elt = bag `unionBags` (unitBag elt)
isEmptyBag EmptyBag = True