index package:foldl

(index n) returns the nth element of the container, or Nothing if the container has an insufficient number of elements

(index n) returns the nth byte of the byte stream, or Nothing if the stream has an insufficient number of bytes

(index n) returns the nth character of the text stream, or Nothing if the stream has an insufficient number of characters

(elemIndex a) returns the index of the first element that equals a, or Nothing if no element matches

(findIndex predicate) returns the index of the first element that satisfies the predicate, or Nothing if no element satisfies the predicate

Like index, except with a more general Integral argument

(elemIndex w8) returns the index of the first byte that equals w8, or Nothing if no byte matches

(findIndex predicate) returns the index of the first byte that satisfies the predicate, or Nothing if no byte satisfies the predicate

(elemIndex c) returns the index of the first character that equals c, or Nothing if no character matches

(findIndex predicate) returns the index of the first character that satisfies the predicate, or Nothing if no character satisfies the predicate