How to quicksort list of lists in prolog?

@orpha 

Quicksort is a sorting algorithm that can be used in Prolog to sort a list of lists. Here is an implementation of quicksort in Prolog for sorting a list of lists:

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quicksort([], []).
quicksort([H|T], Sorted) :-
    partition(H, T, Left, Right),
    quicksort(Left, SortedLeft),
    quicksort(Right, SortedRight),
    append(SortedLeft, [H|SortedRight], Sorted).

partition(_, [], [], []).
partition(Pivot, [H|T], [H|Left], Right) :-
    H @=< Pivot,
    partition(Pivot, T, Left, Right).
partition(Pivot, [H|T], Left, [H|Right]) :-
    H @> Pivot,
    partition(Pivot, T, Left, Right).

To use this implementation, you can simply call quicksort/2 predicate with the list you want to sort as the first argument and a variable to hold the sorted list as the second argument. Here is an example:

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?- quicksort([[3, 1], [2, 4], [1, 3]], Sorted).
Sorted = [[1, 3], [2, 4], [3, 1]].

This will sort the list of lists in ascending order based on the first element of each list. If you want to customize the sorting criteria, you can modify the partition/4 predicate accordingly.