[Haskell-cafe] Re: Simple Fudgets-question

[Henrik Berg]

Thomas Hallgren <hallgren at cse.ogi.edu> writes:

> Henrik Berg wrote:
>
>>Hi!
>>
>>I can't find any function in the Fudgets-library to do this:
>>
>>(F a b) -> (F a (a, b))
>>
>>... All I want to do is to resend the input out on the output.
>>
>>
> If that is all you want, this combinator is the right choice:
>
> 	throughF :: F a b -> F a (Either b a)
>

Yes, but (Either b a) won't give me the input _together_ with the
output, will it?  I need a fudget that accepts some input, does some
work on it, and outputs the result _and_ the original input for
further processing by other fudgets.  As far as I can see, this means
I need a tupple (a, b), and not the disjoint sum (Either a b).

-- 
Henrik