I had some free time this afternoon so I put together an (experimental) patch for GHC that implements helpful errors messages. Have a look at this GHCi session to see what I mean: "" $ stage2/ghc-inplace --interactive -fhelpful-errors GHCi, version 6.9.20080711: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer ... linking ... done. Loading package base ... linking ... done. Prelude> let foo = 10 Prelude> foa <interactive>:1:0: Not in scope: `foa' Maybe you meant one of: `foo' `fst' `not' -- Maybe the matching threshold could stand to be tweaked a bit, e.g. scaled with identifier string length.. Prelude> let myIdentifier = 10 Prelude> myIdentfiier <interactive>:1:0: Not in scope: `myIdentfiier' Maybe you meant `myIdentifier' Prelude> "" The feature was inspired by the equivalent feature in the Boo programming language (http://boo.codehaus.org/). I use the restricted Damerau–Levenshtein distance to do the fuzzy match (http://en.wikipedia.org/wiki/Damerau-Levenshtein_distance). What do you think about this feature? Would it be genuinely helpful or annoying? Max