[Haskell-beginners] Questions on data/type
jason.dusek at gmail.com
Tue Nov 17 01:11:32 EST 2009
2009/11/15 Matthew Wong <matwong at rogers.com>:
> If I want to express the following idea (the following won't compiler):
> data TypeCon a = ValConA a | ValConB [ValConA a] | ValConC [ValConB a]
In this definition, you are confusing constructors with types.
You can't have a list of `ValConB a` -- the type is actually
> The alternative is use 3 different type constructors,
> data TypeConA a = ValConA a
> data TypeConB a = ValConB a
> data TypeConC a = ValConC a
This is more promising. I'd need to see the typeclass you're
trying to define to say more.
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