Re: [Haskell-cafe] Question about arrows

On 8/3/07, Lewis-Sandy, Darrell wrote:

Is there a class property of the Control.Arrow class that represents the evaluatation of an arrow:

eval :: (Arrow a)=>a b c->b->c

You could always use the ArrowEval class. Granted, it doesn't exist, so you'd have to write it, but it should serve your purposes. class ArrowEval a where eval :: a b c -> b -> c instance ArrowEval (->) where eval = ... instance ArrowEval YourPartial where eval = ... (That's off the cuff, so I probably didn't get the syntax correct.) Does that fit your problem? But like Mr. Morris said, eval isn't valid for every arrow, so you can only define instances of ArrowEval where it is valid. Bryan