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

--  See license.txt for further details


with

    Ada.Text_IO,
    Kompsos.Pretty_Print;


procedure FiveSix is

    package TIO renames Ada.Text_IO;


    package InKomp is new Kompsos (Integer);
    use InKomp;

    package InPrin is new InKomp.Pretty_Print (Integer'Image);
    use InPrin;


    --  It is possible to create a recursion using functions like this...
    function Fives
           (This : in World)
        return World
    is
        One, Two : World := This;
    begin
        One.Unify (One.Fresh, 5);
        Two.Conjunct (Fives'Access);
        return Disjunct (One, Two);
    end Fives;


    Sixes : World := Empty_World;
    Result : World;

begin

    TIO.Put_Line ("Test program for fives-and-sixes example from 2013 microKanren paper.");
    TIO.Put_Line ("Since the result is infinite, only the first five states will be shown.");

    TIO.New_Line;

    --  ...but it is a lot simpler and easier to create recursions this way instead.
    Sixes.Unify (Sixes.Fresh, 6);
    Sixes.Recurse;

    Result := Disjunct (Fives (Empty_World), Sixes);

    --  Note how the States from Fives keep creating new Variables instead of looping.
    TIO.Put_Line (Image (Result.Take (5)));

end FiveSix;