Haskell map/zip Vs. list comprehension
Which of the following are you most likely to write?
r = zip xs $ map sqrt xs
or
r = [(x, sqrt x) | x <- xs]
Sample code on the Internet seems to indicate that the former is more abundant and the preferred way.
Answer
People who spend too much time in #haskell would probably write that as
r = map (id &&& sqrt) xs
(&&&) is a fun combinator defined in Control.Arrow. Its actual type signature is complicated because it's generalized to all instances of Arrow. But it's often used with the (->) instance of Arrow, which results in this type signature:
(&&&) :: (a -> b) -> (a -> c) -> a -> (b, c)