> module FiniteHugs where

> type FiniteMap key elt = [(key,elt)]

> emptyFM :: (Ord key) => FiniteMap key elt
> emptyFM = []

> addToFM :: (Ord key) => FiniteMap key elt -> key -> elt  -> FiniteMap key elt
> addToFM [] key elt = [(key,elt)]
> addToFM fm@(f:m) key elt = ((key,elt):fm)

> listToFM :: (Ord key) => [(key,elt)] -> FiniteMap key elt
> listToFM l = foldr (\(k,e) n -> addToFM n k e) emptyFM l

> delFromFM :: (Ord key) => FiniteMap key elt -> key   -> FiniteMap key elt
> delFromFM fm key = fm

> lookupFM :: (Ord key) => FiniteMap key elt -> key -> Maybe elt -- XXX Eq????
> lookupFM list n = let res = (filter (\(k,e) -> k == n) list) in
>   case res of
>     [] -> Nothing
>     ((k,e):_) -> Just e

> unitFM :: (Ord key) => key -> elt -> FiniteMap key elt
> unitFM key elt = addToFM emptyFM key elt

> mapFM :: (key -> elt1 -> elt2) -> FiniteMap key elt1 -> FiniteMap key elt2
> mapFM f fm = map (\(k,e) -> (k,f k e)) fm

> fmToList :: (Ord key) => FiniteMap key elt -> [(key,elt)]
> fmToList fm = fm