Hi Alistair, http://haskell.org/hoogle/?q=typeOf C:\>ghci GHCi, version 6.8.1: http://www.haskell.org/ghc/ :? for help Loading package base ... linking ... done. Prelude> :m Data.Typeable Prelude Data.Typeable> typeOf "neil" [Char] Thanks Neil On 12/14/07, Alistair Bayley wrote:

I've been learning/playing with Data.Generics a bit, and have a how-to question...

...

dataTypeOf ""

If I say then I get

...

DataType {tycon = "Prelude.[]", datarep = AlgRep [[],(:)]}

No surprises there. But I'd really like to know that I have a String, or [Char]. How do I get the name of the concrete type that the list contains? Is that a reasonable thing to ask for?

I can say:

...

gmapQ dataTypeOf "a" to get: [ DataType {tycon = "Prelude.Char", datarep = StringRep} , DataType {tycon = "Prelude.[]", datarep = AlgRep [[],(:)]} ]

But if I say:

...

gmapQ dataTypeOf "" I get: []

which makes sense when you consider the stucture of the List ADT, but doesn't help me determine the type of the value.

Alistair _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe