99 questions/Solutions/15: Difference between revisions

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(added solution using list monad)
Line 15: Line 15:
repli :: [a] -> Int -> [a]
repli :: [a] -> Int -> [a]
repli xs n = concatMap (take n . repeat) xs
repli xs n = concatMap (take n . repeat) xs
</haskell>
or, using the list monad:
<haskell>
repli :: [a] -> Int -> [a]
repli xs n = xs >>= replicate n
</haskell>
</haskell>

Revision as of 14:21, 5 August 2011

(**) Replicate the elements of a list a given number of times.

repli :: [a] -> Int -> [a]
repli xs n = concatMap (replicate n) xs

or, in Pointfree style:

repli = flip $ concatMap . replicate

alternatively, without using the replicate function:

repli :: [a] -> Int -> [a]
repli xs n = concatMap (take n . repeat) xs

or, using the list monad:

repli :: [a] -> Int -> [a]
repli xs n = xs >>= replicate n