Difference between revisions of "99 questions/Solutions/4"
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< 99 questions | Solutions
(correction (foldl) and shortened version of foldr) |
Citizen428 (talk | contribs) m |
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myLength'' = foldr (\_ n -> n + 1) 0 | myLength'' = foldr (\_ n -> n + 1) 0 | ||
myLength''' = foldr (\_ -> (+1)) 0 | myLength''' = foldr (\_ -> (+1)) 0 | ||
| + | </haskell> | ||
| + | |||
| + | <haskell> | ||
| + | myLength' xs = snd $ last $ zip xs [1..] -- Just for fun | ||
</haskell> | </haskell> | ||
This is <hask>length</hask> in <hask>Prelude</hask>. | This is <hask>length</hask> in <hask>Prelude</hask>. | ||
Revision as of 22:46, 1 December 2010
(*) Find the number of elements of a list.
myLength :: [a] -> Int
myLength [] = 0
myLength (_:xs) = 1 + myLength xs
myLength' = foldl (\n _ -> n + 1) 0
myLength'' = foldr (\_ n -> n + 1) 0
myLength''' = foldr (\_ -> (+1)) 0
myLength' xs = snd $ last $ zip xs [1..] -- Just for fun
This is length in Prelude.