Re: [Haskell-cafe] where to put handy functions?

Hmm, this would make a good QuickCheck property. I wonder, is listify a contravariant functor? Fun to work through the details of that some time, I think. Chad On 8/10/07, Brent Yorgey wrote:

Amusingly, extract is intimately related to function composition. Suppose we have

listify :: (Int -> Int) -> [Int] listify = flip map [0..]

Then if f, g :: Int -> Int, and f is monotonically increasing, we have the identity

(listify f) `extract` (listify g) = listify (g . f)

This randomly occurred to me as I was falling asleep last night and I thought I would share. =)

-Brent