[Haskell-beginners] Exercise of "Programming with Arrows"

[Kim-Ee Yeoh]

On Wed, Oct 16, 2013 at 10:33 PM, Thiago Negri <evohunz at gmail.com> wrote:
> Updated gist: https://gist.github.com/thiago-negri/2e541a9f9762c727bdd4

Here:

prop_SP_first :: SP Int Int -> [(Int,Int)] -> Bool
prop_SP_first f xs = x1 == x2
  where x1 = map snd xs
        x2 = map snd (runSP (first f) xs)

you check that the second half of the coupled stream are equal, i.e. the
(arr id) input of (***) is equivalent across the equal sign:

g *** (arr id) = first g

What about the first half?

-- Kim-Ee
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