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:
http://www.haskell.org/ghc/docs/latest/html/libraries/base-4.3.1.0/Control-Arrow.html#v
:loop
If your arrows are instances of ArrowApply, I believe you could use
app to implement the combinator you want.
Cheers,
-Matt
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