Gregory Propf wrote:
Say I have something like
data DT a = Foo a | Bar a | Boo a
I want something like a list of the constructors of DT, perhaps as [TypeRep]. I'm using Data.Typeable but can't seem to find what I need in there. Everything there operates over constructors, not types.
The approach below won't work in general because the constructors may have different (argument) types, but for the above: [Foo, Bar, Boo] :: [a -> DT a] And you could manually build a list of constructor types, as a try: [typeOf Nothing, typeOf Just] :: [TypeRep] which doesn't work, due to polymorphic ambiguity, so you'd have to: [typeOf (Nothing :: Maybe Int), typeOf (Just :: Int -> Maybe Int)] In general, maybe Data.Dynamic is what you need, but I don't think that can handle polymorphic values yet either. What do you want to do with the list of constructors once you have them? Where are they defined? Claude -- http://claudiusmaximus.goto10.org