[Haskell-cafe] ArrowLoop and streamprocessors
mdsteele at alum.mit.edu
Thu Mar 31 17:01:51 CEST 2011
On Mar 30, 2011, at 5:29 PM, Mathijs Kwik wrote:
> So loop really doesn't seem to help here, but I couldn't find another
> way either to feed outputs back into the system.
> What I need is:
> Either A B ~> Either C B -> A ~> C
> Does such a thing exist?
Based on your description, it sounds to me like you want a loop such
that if a B is generated at the end, you send it back to the start and
execute your arrow a second time. Is that in fact what you intended?
However, the docs for ArrowLoop's loop function make it clear that it
executes the arrow only once:
If your arrows are instances of ArrowApply, I believe you could use
app to implement the combinator you want.
More information about the Haskell-Cafe