Hello,
Many texts explain the following Fibonacci code:
fibs :: [Integer]
fibs = 0 : 1 : zipWith (+) fibs (tail fibs)
But this code is very slow because evaluation of (+) is done
lazily. If we have the following strict zipWith', the code above
becomes much faster.
zipWith' f (a:as) (b:bs) = x `seq` x : zipWith' f as bs
where
x = f a b
zipWith' _ _ _ = []
Data.List defines foldl' against foldl. But it does not define
zipWith'. I'm curious why zipWith' does not exist in the standard
libraries.
--Kazu
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