A-M baby

Task/Menu/Haskell/menu-1.hs

@@ -0,0 +1,24 @@
+module RosettaSelect where
+
+import Data.Maybe (listToMaybe)
+import Control.Monad (guard)
+
+select :: [String] -> IO String
+select []   = return ""
+select menu = do
+  putStr $ showMenu menu
+  putStr "Choose an item: "
+  choice <- getLine
+  maybe (select menu) return $ choose menu choice
+
+showMenu :: [String] -> String
+showMenu menu = unlines [show n ++ ") " ++ item | (n, item) <- zip [1..] menu]
+
+choose :: [String] -> String -> Maybe String
+choose menu choice = do
+  n <- maybeRead choice
+  guard $ n > 0
+  listToMaybe $ drop (n-1) menu
+
+maybeRead :: Read a => String -> Maybe a
+maybeRead = fmap fst . listToMaybe . filter (null . snd) . reads

Task/Menu/Haskell/menu-2.hs

@@ -0,0 +1,8 @@
+*RosettaSelect> select ["fee fie", "huff and puff", "mirror mirror", "tick tock"]
+1) fee fie
+2) huff and puff
+3) mirror mirror
+4) tick tock
+Choose an item: 3
+"mirror mirror"
+*RosettaSelect>