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