The generic interface ListSort extends the generic interface List with sorting operations. \index{sorting!lists}

GENERIC INTERFACE ListSort(Elem, ElemList);

Where Elem.T is not an open array type, ElemList equals List(Elem), and Elem contains

      CONST Brand = <text-constant>;
      PROCEDURE Compare(e1, e2: Elem.T): [-1..1];

Brand must be a text constant. It will be used to construct a brand for any generic types instantiated with the ListSort interface. For a non-generic interface, we recommend choosing the name of the interface.

Compare must be a total order. It may be declared with any parameter mode, but must have no visible side-effects.

CONST Brand = "(ListSort " & Elem.Brand & ")";

TYPE T = ElemList.T;

PROCEDURE Sort(l: T; c := Elem.Compare): T;
PROCEDURE SortD(l: T; c := Elem.Compare): T;

Sort a list in ascending order using c to compare pairs of elements of l.

END ListSort.