# 99 questions/Solutions/4

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< 99 questions | Solutions

Revision as of 01:39, 20 November 2010 by Drb226 (talk | contribs) (correction (foldl) and shortened version of foldr)

(*) 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
```

This is `length`

in `Prelude`

.