structure ROOT =
struct
structure Code_Generator =
struct
type 'a eq = {eq : 'a -> 'a -> bool};
fun eq (A_:'a eq) = #eq A_;
end; (*struct Code_Generator*)
structure List =
struct
fun foldr f (x :: xs) a = f x (foldr f xs a)
| foldr f [] a = a;
fun memberl A_ x (y :: ys) =
Code_Generator.eq A_ x y orelse memberl A_ x ys
| memberl A_ x [] = false;
end; (*struct List*)
structure Set =
struct
datatype 'a set = Set of 'a list;
val empty : 'a set = Set [];
fun insert x (Set xs) = Set (x :: xs);
fun uniona xs (Set ys) = List.foldr insert ys xs;
fun union (Set xs) = List.foldr uniona xs empty;
fun member A_ x (Set xs) = List.memberl A_ x xs;
end; (*struct Set*)
end; (*struct ROOT*)