Re: [Haskell-cafe] Question, re: type class syntax.

Thanks, Will. Maybe I’ve got the syntax all wrong, but my intent is just to constrain the type ’t’ to be of class 'LogTree2 a’. -db On Aug 29, 2015, at 5:27 PM, William Yager wrote:

If you want the "LogTree2" typeclass to have multiple type arguments (which it looks like you do, from the definition of "evaluator"), you need to define it as

class (Show a, Num a) => LogTree2 a t where

--Will

On Sat, Aug 29, 2015 at 6:45 PM, David Banas wrote: Hi all,

I can’t figure out why this is invalid:

class (Show a, Num a) => LogTree2 a where evaluator :: (LogTree2 a) t => t -> SizedVector a -> SizedVector a

error| ‘LogTree2’ is applied to too many type arguments In the type ‘(LogTree2 a) t => t -> SizedVector a -> SizedVector a’ In the class declaration for ‘LogTree2’

Can anyone help me understand?

Thanks, -db

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