Modified eqvt_tac to avoid failure due to introduction rules
whose premises contain variables that do not occur in the
conclusion.
structure ROOT =
struct
structure Code_Generator =
struct
type 'a eq = {op_eq : 'a -> 'a -> bool};
fun op_eq (A_:'a eq) = #op_eq A_;
end; (*struct Code_Generator*)
structure List =
struct
fun memberl A_ x (y :: ys) =
Code_Generator.op_eq A_ x y orelse memberl A_ x ys
| memberl A_ x [] = false;
end; (*struct List*)
structure Codegen =
struct
fun collect_duplicates A_ xs ys (z :: zs) =
(if List.memberl A_ z xs
then (if List.memberl A_ z ys then collect_duplicates A_ xs ys zs
else collect_duplicates A_ xs (z :: ys) zs)
else collect_duplicates A_ (z :: xs) (z :: ys) zs)
| collect_duplicates A_ xs ys [] = xs;
end; (*struct Codegen*)
end; (*struct ROOT*)