:: (a -> Bool) -> [a] -> [a] package:extra

A version of dropWhileEnd but with different strictness properties. The function dropWhileEnd can be used on an infinite list and tests the property on each character. In contrast, dropWhileEnd' is strict in the spine of the list but only tests the trailing suffix. This version usually outperforms dropWhileEnd if the list is short or the test is expensive. Note the tests below cover both the prime and non-prime variants.

dropWhileEnd  isSpace "ab cde  " == "ab cde"
dropWhileEnd' isSpace "ab cde  " == "ab cde"
last (dropWhileEnd  even [undefined,3]) == undefined
last (dropWhileEnd' even [undefined,3]) == 3
head (dropWhileEnd  even (3:undefined)) == 3
head (dropWhileEnd' even (3:undefined)) == undefined

A version of takeWhile operating from the end.

takeWhileEnd even [2,3,4,6] == [4,6]