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Try to print A = B instead of A = _X, B = _X when two variables are equal

--- a/repl.pl

+++ b/repl.pl

@@ -35,8 +35,9 @@

 	!,

 	abolish(found_a_solution/0).

-eval_and_print(Goal, Vars, Choicecount) :-

+eval_and_print(Goal, Vars0, Choicecount) :-

 	user:call(Goal),

+	rewrite_equations(Vars0, Vars),

 	abolish(found_a_solution/0),

 	asserta(found_a_solution :- !),

 	'$choicestack_size'(ChoicecountNew),

@@ -58,6 +59,26 @@

 	write('false.'),

 	nl.

+rewrite_equations(Eqs0, Eqs) :-

+	apply_bindings(Eqs0),

+	remove_identities(Eqs0, Eqs).

+

+apply_bindings([]).

+apply_bindings([A = B|Rest]) :-

+	( var(B)

+	-> call(B = A)

+	; true

+	),

+	apply_bindings(Rest).

+

+remove_identities([], []).

+remove_identities([A = B|Rest0], Result) :-

+	remove_identities(Rest0, Rest),

+	( A == B

+	-> Result = Rest

+	; Result = [A = B|Rest]

+	).

+

 write_state(end) :- write('.'), nl.

 write_state(more).

@@ -68,7 +89,7 @@

 write_bindings([Var = Val|Bs]) :-

 	write(Var),

 	write(' = '),

-	writeq(Val),

+	write(Val),

 	( Bs = []

 	-> true

 	; put_char(','), nl