--  Programmed by Jedidiah Barber
--  Licensed under the Sunset License v1.0

--  See license.txt for further details


package body Kompsos.Prelude is


    function Head
           (This                 : in World;
            Full_List, Head_Term : in Term'Class)
        return World is
    begin
        return Result : World := This do
            Result.Unify (T (Head_Term & T (Result.Fresh)), Full_List);
        end return;
    end Head;

    procedure Head
           (This                 : in out World;
            Full_List, Head_Term : in     Term'Class) is
    begin
        This := Head (This, Full_List, Head_Term);
    end Head;


    function Tail
           (This                 : in World;
            Full_List, Tail_Term : in Term'Class)
        return World is
    begin
        return Result : World := This do
            Result.Unify (T (T (Result.Fresh) & Tail_Term), Full_List);
        end return;
    end Tail;

    procedure Tail
           (This                 : in out World;
            Full_List, Tail_Term : in     Term'Class) is
    begin
        This := Tail (This, Full_List, Tail_Term);
    end Tail;


    function Cons
           (This                            : in World;
            Head_Term, Tail_Term, Full_List : in Term'Class)
        return World is
    begin
        return Result : World := This do
            Result.Unify (T (Head_Term & Tail_Term), Full_List);
        end return;
    end Cons;

    procedure Cons
           (This                            : in out World;
            Head_Term, Tail_Term, Full_List : in     Term'Class) is
    begin
        This := Cons (This, Head_Term, Tail_Term, Full_List);
    end Cons;


    function Nil
           (This     : in World;
            Nil_Term : in Term'Class)
        return World is
    begin
        return Result : World := This do
            Result.Unify (Null_Term, Nil_Term);
        end return;
    end Nil;

    procedure Nil
           (This     : in out World;
            Nil_Term : in     Term'Class) is
    begin
        This := Nil (This, Nil_Term);
    end Nil;


    function Pair
           (This      : in World;
            Pair_Term : in Term'Class)
        return World is
    begin
        return Result : World := This do
            Result.Unify (T (T (Result.Fresh), T (Result.Fresh)), Pair_Term);
        end return;
    end Pair;

    procedure Pair
           (This      : in out World;
            Pair_Term : in     Term'Class) is
    begin
        This := Pair (This, Pair_Term);
    end Pair;


end Kompsos.Prelude;