[Haskell-cafe] Implicit parameters and Arrows/Yampa?

Peter Verswyvelen bf3 at telenet.be
Sun Jan 6 17:44:51 EST 2008


If I understand it correctly, implicit parameters in Haskell allow you to
pass values to functions with explicitly adding a parameter to each of the
functions being "called" (I appologize for my imperative terminology here.
How would I say this correctly? Being "evaluated"?)

 

The arrows always use tuples to group the input and output parameters, like:

 

foo :: SF (Int,Int,Int) (Int,Int)

foo = proc (x,y,z) -> do

   p <- cat -< (x,y)

   q <- dog -< z

   returnA -< (p,q)

     where

       cat = proc (x,y) -> returnA -< (x+y)

       dog = proc z -> returnA -< 10*z

 

Suppose I don't want to explicitly pass the x and y parameters to the cat
(and deeper) arrows, but make them implicit. I guess that would be
impossible? I mean, I can't use implicit parameters language extension to
make the arrow input parameters implicit?

 

Thanks,

Peter

 

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