99 questions/Solutions/4
< 99 questions | Solutions
Jump to navigation
Jump to search
The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.
(*) Find the number of elements of a list.
myLength :: [a] -> Int
myLength [] = 0
myLength (_:xs) = 1 + myLength xs
myLength' :: [a] -> Int
myLength' list = myLength_acc list 0 -- same, with accumulator
where
myLength_acc [] n = n
myLength_acc (_:xs) n = myLength_acc xs (n + 1)
myLength' = foldl (\n _ -> n + 1) 0
myLength'' = foldr (\_ n -> n + 1) 0
myLength''' = foldr (\_ -> (+1)) 0
myLength'''' = foldr ((+) . (const 1)) 0
myLength''''' = foldr (const (+1)) 0
myLength' xs = snd $ last $ zip xs [1..] -- Just for fun
myLength'' = snd . last . (flip zip [1..]) -- Because point-free is also fun
myLength''' = fst . last . zip [1..] -- same, but easier
myLength = sum . map (\x -> 1)
myLength = foldl (const . (+1)) 0
This is length
in Prelude
.