Thank guys, Now what am I misunderstanding in the code below? I would think that *Main> comb (Just 65) foo and *Main> comb (lookup 'A' lst) foo would return the same result Just 'A' Michael ===========Haskell code============= import Data.Char lst = [('A',65),('B',66),('C',67),('D',68)] -- comb is a combinator for sequencing operations that return Maybe comb :: Maybe a -> (a -> Maybe b) -> Maybe b comb Nothing  _ = Nothing comb (Just x) f = f x foo :: Int -> Maybe Char foo n = Just (chr n) ================Ghci=========== [michael@localhost ~]$ ghci GHCi, version 6.10.1: http://www.haskell.org/ghc/  :? for help Loading package ghc-prim ... linking ... done. Loading package integer ... linking ... done. Loading package base ... linking ... done. Prelude> :load test1 [1 of 1] Compiling Main             ( test1.hs, interpreted ) Ok, modules loaded: Main. *Main> comb (Just 65) foo Just 'A' *Main> comb Nothing foo Nothing *Main> lookup 'A' lst Just 65 *Main> (lookup 'A' lst) Just 65 *Main> comb (lookup 'A' lst) foo <interactive>:1:22:     Couldn't match expected type `Integer' against inferred type `Int'     In the second argument of `comb', namely `foo'     In the expression: comb (lookup 'A' lst) foo     In the definition of `it': it = comb (lookup 'A' lst) foo *Main> --- On Tue, 4/28/09, Lennart Augustsson wrote: From: Lennart Augustsson Subject: Re: [Haskell-cafe] chr/ord? To: "Tim Wawrzynczak" Cc: "michael rice" , "haskell-cafe@haskell.org" Date: Tuesday, April 28, 2009, 10:53 PM You can also use the more general toEnum and fromEnum.     -- Lennart (iPhone) On Apr 29, 2009, at 2:13, Tim Wawrzynczak wrote: Michael, those functions are not in the Prelude, they're in Data.Char. On Tue, Apr 28, 2009 at 8:08 PM, michael rice wrote: Hi, My Prelude docs must be out of date because chr and ord don't seem to be there. How do I access these functions? Michael =============== [michael@localhost ~]$ ghci GHCi, version 6.10.1: http://www.haskell.org/ghc/  :? for help Loading package ghc-prim ... linking ... done. Loading package integer ... linking ... done. Loading package base ... linking ... done. Prelude> chr 65 <interactive>:1:0: Not in scope: `chr' Prelude> ord 'A' <interactive>:1:0: Not in scope: `ord' Prelude> _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe