Copyright	(C) 2014-2016 Edward Kmett and Eric Mertens
License	BSD-style (see the file LICENSE)
Maintainer	Edward Kmett <ekmett@gmail.com>
Stability	provisional
Portability	non-portable
Safe Haskell	Safe-Inferred
Language	Haskell2010

Control.Lens.Internal.List

Description

This module provides utility functions on lists used by the library implementation.

Synopsis

ordinalNub :: Int -> [Int] -> [Int]
stripSuffix :: Eq a => [a] -> [a] -> Maybe [a]

Documentation

ordinalNub Source #

Arguments

:: Int	strict upper bound
-> [Int]	ordinals
-> [Int]	unique, in-bound ordinals, in order seen

Return the the subset of given ordinals within a given bound and in order of the first occurrence seen.

Bound: 0 <= x < l

>>> ordinalNub 3 [-1,2,1,4,2,3]
[2,1]

stripSuffix :: Eq a => [a] -> [a] -> Maybe [a] Source #

\(\mathcal{O}(\min(m,n))\). The stripSuffix function drops the given suffix from a list. It returns Nothing if the list did not end with the suffix given, or Just the list after the suffix, if it does.

>>> stripSuffix "bar" "foobar"
Just "foo"

>>> stripSuffix "foo" "foo"
Just ""

>>> stripSuffix "bar" "barfoo"
Nothing

>>> stripSuffix "foo" "barfoobaz"
Nothing