Sorting Lists

sort2+List, -Sorted Succeeds if Sorted can be unified with a list holding the elements of List, sorted to the standard order of terms (see compare). Duplicates are removed. Implemented by translating the input list into a temporary array, calling the C-library function qsort3 using PL_compare for comparing the elements, after which the result is translated into the result list. msort2+List, -Sorted Equivalent to sort2, but does not remove duplicates. keysort2+List, -Sorted List is a list of Key-Value pairs (e.g. terms of the functor `' with arity 2). keysort2 sorts List like msort2, but only compares the keys. Can be used to sort terms not on standard order, but on any criterion that can be expressed on a multi-dimensional scale. Sorting on more than one criterion can be done using terms as keys, putting the first criterion as argument 1, the second as argument 2, etc. The order of multiple elements that have the same Key is not changed. predsort3+Pred, +List, -Sorted Sorts similar to sort2, but determines the order of two terms by calling Pred(-Delta, +E1, +E2). This call must unify Delta with one of , const or . If built-in predicate compare3 is used, the result is the same as sort2. See also keysort2.^2.11