filter takes as its arguments a function that returns a boolean (that is: a predicate) and a list. It then applies the function to each element in the function and constructs a new list that consists of the elements for which the predicate returned 0.
Perl's implementation of the filter function is grep.
The shell command grep and Windows console commands find.exe and findstr.exe might be considered a sort of a filter function (in which each line of a text file is an element of a list).