--- /dev/null
+:- use_module(library(clpfd)).
+
+%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+
+process(Program, ReducedProgram) :-
+ findall(PC1, (member(C1, Program), preduce(C1, PC1), portray_clause(PC1)), ReducedProgram).
+
+preduce( (A :- B), (Pa :- Pb) ) :- !, preduce(B, Pb), preduce(A, Pa).
+preduce( true, true ) :- !.
+preduce( (A, B), Residue ) :- !, preduce(A, Pa), preduce(B, Pb), combine(Pa, Pb, Residue).
+preduce( A, B ) :- should_fold(A, B), !.
+preduce( A, Residue ) :- should_unfold(A), !, clause(A, B), preduce(B, Residue).
+preduce( A, A ).
+
+combine(true, B, B) :- !.
+combine(A, true, A) :- !.
+combine(A, B, (A, B)).
+
+test(Name, Program) :- program(Name, Clauses), process(Clauses, Program).
+
+%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+
+program(tundra, [
+ ( thun([], S, S) ),
+ ( thun( [Lit|E], Si, So) :- literal(Lit), thun(E, [Lit|Si], So) ),
+ ( thun( [Func|E], Si, So) :- func(Func, Si, S), thun(E, S, So) ),
+ ( thun([Combo|E], Si, So) :- combo(Combo, Si, S, E, Eo), thun(Eo, S, So) )
+ ]).
+
+should_unfold(func(Func, Si, So)).
+should_unfold(combo(A, B, C, D, E)).
+should_unfold(literal(Lit)).
+should_fold(sam, bill).
+
+%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+
+literal(V) :- var(V).
+literal(I) :- number(I).
+literal([]).
+literal([_|_]).
+literal(true).
+literal(false).
+
+func(cons, [A, B|S], [[B|A]|S]).
+func(swap, [A, B|S], [B, A|S]).
+func(dup, [A|S], [A, A|S]).
+func(pop, [_|S], S ).
+func(+, [A, B|S], [C|S]) :- C #= A + B.
+func(-, [A, B|S], [C|S]) :- C #= B - A.
+func(*, [A, B|S], [C|S]) :- C #= A * B.
+func(/, [A, B|S], [C|S]) :- C #= B div A.
+
+func(nullary, [P|S], [X|S]) :- thun(P, S, [X|_]). % Combinator.
+func(infra, [P, R|S], [Q|S]) :- thun(P, R, Q). % Combinator.
+
+func(concat, [A, B|S], [C|S]) :- append(B, A, C).
+func(flatten, [A|S], [B|S]) :- flatten(A, B).
+func(swaack, [R|S], [S|R]).
+func(stack, S , [S|S]).
+func(clear, _ , []).
+func(first, [[X|_]|S], [X|S]).
+func(rest, [[_|X]|S], [X|S]).
+func(unit, [X|S], [[X]|S]).
+
+combo(i, [P|S], S, Ei, Eo) :- append(P, Ei, Eo).
+combo(dip, [P, X|S], S, Ei, Eo) :- append(P, [X|Ei], Eo).
+combo(dipd, [P, X, Y|S], S, Ei, Eo) :- append(P, [Y, X|Ei], Eo).
+
+%-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+
+% ?- test(tundra, _).
+% thun([], A, A).
+% thun([A|B], C, D) :- var(A), thun(B, [A|C], D).
+% thun([A|B], C, D) :- number(A), thun(B, [A|C], D).
+% thun([[]|A], B, C) :- thun(A, [[]|B], C).
+% thun([[B|C]|A], D, E) :- thun(A, [[B|C]|D], E).
+% thun([true|A], B, C) :- thun(A, [true|B], C).
+% thun([false|A], B, C) :- thun(A, [false|B], C).
+% thun([cons|A], [C, B|D], E) :- thun(A, [[B|C]|D], E).
+% thun([swap|A], [C, B|D], E) :- thun(A, [B, C|D], E).
+% thun([dup|A], [B|C], D) :- thun(A, [B, B|C], D).
+% thun([pop|A], [_|B], C) :- thun(A, B, C).
+% thun([+|E], [A, B|F], G) :-
+% ( integer(C)
+% -> ( integer(A),
+% integer(B)
+% -> C=:=A+B
+% ; D=C,
+% clpfd:clpfd_equal(D, A+B)
+% )
+% ; integer(A),
+% integer(B)
+% -> ( var(C)
+% -> C is A+B
+% ; D is A+B,
+% clpfd:clpfd_equal(C, D)
+% )
+% ; clpfd:clpfd_equal(C, A+B)
+% ),
+% thun(E, [C|F], G).
+% thun([-|E], [B, A|F], G) :-
+% ( integer(C)
+% -> ( integer(A),
+% integer(B)
+% -> C=:=A-B
+% ; D=C,
+% clpfd:clpfd_equal(D, A-B)
+% )
+% ; integer(A),
+% integer(B)
+% -> ( var(C)
+% -> C is A-B
+% ; D is A-B,
+% clpfd:clpfd_equal(C, D)
+% )
+% ; clpfd:clpfd_equal(C, A-B)
+% ),
+% thun(E, [C|F], G).
+% thun([*|E], [A, B|F], G) :-
+% ( integer(C)
+% -> ( integer(A),
+% integer(B)
+% -> C=:=A*B
+% ; D=C,
+% clpfd:clpfd_equal(D, A*B)
+% )
+% ; integer(A),
+% integer(B)
+% -> ( var(C)
+% -> C is A*B
+% ; D is A*B,
+% clpfd:clpfd_equal(C, D)
+% )
+% ; clpfd:clpfd_equal(C, A*B)
+% ),
+% thun(E, [C|F], G).
+% thun([/|C], [B, A|E], F) :- D#=A div B, thun(C, [D|E], F).
+% thun([nullary|C], [A|B], E) :- thun(A, B, [D|_]), thun(C, [D|B], E).
+% thun([infra|C], [A, B|E], F) :- thun(A, B, D), thun(C, [D|E], F).
+% thun([concat|C], [B, A|E], F) :- append(A, B, D), thun(C, [D|E], F).
+% thun([flatten|B], [A|D], E) :- flatten(A, C), thun(B, [C|D], E).
+% thun([swaack|A], [C|B], D) :- thun(A, [B|C], D).
+% thun([stack|A], B, C) :- thun(A, [B|B], C).
+% thun([clear|A], _, B) :- thun(A, [], B).
+% thun([first|A], [[B|_]|C], D) :- thun(A, [B|C], D).
+% thun([rest|A], [[_|B]|C], D) :- thun(A, [B|C], D).
+% thun([unit|A], [B|C], D) :- thun(A, [[B]|C], D).
+% thun([i|B], [A|D], E) :- append(A, B, C), thun(C, D, E).
+% thun([dip|C], [A, B|E], F) :- append(A, [B|C], D), thun(D, E, F).
+% thun([dipd|D], [A, C, B|F], G) :- append(A, [B, C|D], E), thun(E, F, G).
+% true.
+
+
+
+
+