Please, what is the matter with Map.lookup ? In ghc-6.4.1, I try -------------------------------
ghci -package base
/ _ \ /\ /\/ __(_) / /_\// /_/ / / | | GHC Interactive, version 6.4.1, for Haskell 98. / /_\\/ __ / /___| | http://www.haskell.org/ghc/ \____/\/ /_/\____/|_| Type :? for help. Loading package base-1.0 ... linking ... done. Prelude> Data.Map.singleton 'a' 'b' {'a':='b'} Prelude> Data.Map.lookup 'a' $ Data.Map.singleton 'a' 'b' Prelude> ------------------------------- Must not it print Just 'b' instead of printing emptyness? Further: ---------- Prelude> Data.Map.lookup 'b' $ Data.Map.singleton 'a' 'b' *** Exception: user error (Data.Map.lookup: Key not found) ---------- Instead, must not it print Nothing ? Thank you in advance for explanation, ----------------- Serge Mechveliani mechvel@botik.ru