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| Module: | List |
|---|---|
| Function: | findIndex |
| Type: | (a -> Bool) -> [a] -> Maybe Int |
| Description: | Function find returns the first element of a list that satisfies a predicate, or Nothing, if there is no such element. findIndex returns the corresponding index. findIndices returns a list of all such indices. |
| Related: | elemIndex, elemIndices, find, findIndices |
Input: findIndex (>3) [0,2,4,6,8]
Output: Just 2
Input: findIndex (==3) [0,2,4,6,8]
Output: Nothing
Input: findIndex even [2,4,6,8]
Output: Just 0
Input: findIndex (\x -> 5**x > 10000) [2,4,6,8]
Output: Just 2