words.lhs

> import qualified Data.Map as M

> vowel :: Char -> Bool
> vowel 'a' = True
> vowel 'e' = True
> vowel 'i' = True
> vowel 'o' = True
> vowel 'u' = True
> vowel _ = False

> vowelStar :: String -> [String]
> vowelStar "" = []
> vowelStar (l : ls) | vowel l   = ('*' : ls) : map (l :) (vowelStar ls)
>                    | otherwise = map (l :) (vowelStar ls)

> main = do
>     h <- readFile "/usr/share/dict/words"
>     let d = [(v, [u]) | u <- words h, v <- vowelStar u]
>     let e = map snd $ M.toList $ M.fromListWith (++) d
>     let f = filter ((== 5) . length) e
>     mapM_ print f

Result is:

["u","o","i","e","a"]
["bug","bog","big","beg","bag"]
["bull","boll","bill","bell","ball"]
["bull's","boll's","bill's","bell's","ball's"]
["bulls","bolls","bills","bells","balls"]
["blunder","blonder","blinder","blender","blander"]
["fur","for","fir","fer","far"]
["lust","lost","list","lest","last"]
["muss","moss","miss","mess","mass"]
["muss's","moss's","miss's","mess's","mass's"]
["musses","mosses","misses","messes","masses"]
["mute","mote","mite","mete","mate"]
["mute's","mote's","mite's","mete's","mate's"]
["mutes","motes","mites","metes","mates"]
["puck","pock","pick","peck","pack"]
["puck's","pock's","pick's","peck's","pack's"]
["pucks","pocks","picks","pecks","packs"]
["pup","pop","pip","pep","pap"]
["pup's","pop's","pip's","pep's","pap's"]
["pups","pops","pips","peps","paps"]
["put","pot","pit","pet","pat"]
["put's","pot's","pit's","pet's","pat's"]
["puts","pots","pits","pets","pats"]
["putted","potted","pitted","petted","patted"]
["putting","potting","pitting","petting","patting"]
["tun","ton","tin","ten","tan"]
["tun's","ton's","tin's","ten's","tan's"]
["tuns","tons","tins","tens","tans"]