> I would like to ask something that results in when I have the following > commands > data Color = Red | Green | Blue | Indigo | Violet deriving (Enum,Show,Read) > (read.show) x > > <interactive>:1:1: > Ambiguous type variable `a' in the constraint: > `Read a' arising from a use of `read' at <interactive>:1:1-4 > Probable fix: add a type signature that fixes these type variable(s)
What the error message says is, it doesn't know which type to read to. read has the type Read a => String -> a, and unless you tell it what 'a' is going to be, how would it know? If you say '(read.show) x :: Color' it should work just fine. Cheers, /Niklas _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
