Cabalize ext-core tools

[ghc-hetmet.git] / utils / ext-core / Language / Core / Env.hs

diff --git a/utils/ext-core/Language/Core/Env.hs b/utils/ext-core/Language/Core/Env.hs
new file mode 100644 (file)
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--- /dev/null
+++ b/utils/ext-core/Language/Core/Env.hs
@@ -0,0 +1,48 @@
+{- Environments.
+  The original version used lists. I changed it to use Data.Map.
+  Sadly it doesn't seem to matter much. --tjc
+-}
+
+module Language.Core.Env (Env,
+           eempty,
+           elookup,
+           eextend,
+            edomain,
+           efromlist,
+            etolist,
+           efilter,
+           eremove)
+where
+
+import qualified Data.Map as M
+
+data Env a b = Env (M.Map a b)
+ deriving Show
+
+eempty :: Env a b 
+eempty = Env M.empty
+
+{- In case of duplicates, returns most recently added entry. -}
+elookup :: (Eq a, Ord a) => Env a b -> a -> Maybe b
+elookup (Env l) k = M.lookup k l 
+
+{- May hide existing entries. -}
+eextend :: Ord a => Env a b -> (a,b) -> Env a b
+eextend (Env l) (k,d) = Env (M.insert k d l)
+
+edomain :: (Eq a) => Env a b -> [a]
+edomain (Env l) = M.keys l
+
+{- In case of duplicates, first entry hides others. -}
+efromlist :: Ord a => [(a,b)] -> Env a b
+efromlist = Env . M.fromList
+
+etolist :: Env a b -> [(a,b)]
+etolist (Env l) = M.toList l
+
+eremove :: (Eq a, Ord a)  => Env a b -> a -> Env a b
+eremove (Env l) k = Env (M.delete k l)
+
+efilter :: Ord a => Env a b -> (a -> Bool) -> Env a b
+efilter (Env l) p = Env (M.filterWithKey (\ k _ -> p k) l)
+