4.24.3 Language-specific comparison

This section deals with predicates for language-specific string comparison operations.

collation_key(+Atom, -Key)

Create a Key from Atom for locale-specific comparison. The key is defined such that if the key of atom A precedes the key of atom B in the standard order of terms, A is alphabetically smaller than B using the sort order of the current locale.

The predicate collation_key/2 is used by locale_sort/2 from library(sort). Please examine the implementation of locale_sort/2 as an example of using this call.

The Key is an implementation-defined and generally unreadable string. On systems that do not support locale handling, Key is simply unified with Atom.

locale_sort(+List, -Sorted)

Sort a list of atoms using the current locale. List is a list of atoms or string objects (see section 5.2). Sorted is unified with a list containing all atoms of List, sorted to the rules of the current locale. See also collation_key/2 and setlocale/3.