commonPrefix
lib.lists.commonPrefix
Docs pulled from | This Revision | 10 minutes ago
The common prefix of two lists.
Inputs
list1-
1. Function argument
list2-
2. Function argument
Type
commonPrefix :: [a] -> [a] -> [a]
Examples
lib.lists.commonPrefix usage example
commonPrefix [ 1 2 3 4 5 6 ] [ 1 2 4 8 ]
=> [ 1 2 ]
commonPrefix [ 1 2 3 ] [ 1 2 3 4 5 ]
=> [ 1 2 3 ]
commonPrefix [ 1 2 3 ] [ 4 5 6 ]
=> [ ]
Noogle detected
Implementation
The following is the current implementation of this function.
commonPrefix =
list1: list2:
let
# Zip the lists together into a list of booleans whether each element matches
matchings = zipListsWith (fst: snd: fst != snd) list1 list2;
# Find the first index where the elements don't match,
# which will then also be the length of the common prefix.
# If all elements match, we fall back to the length of the zipped list,
# which is the same as the length of the smaller list.
commonPrefixLength = findFirstIndex id (length matchings) matchings;
in
take commonPrefixLength list1;