Large Int Set in sml

Question

I'm having the following problem in sml: i want to create a set using the IntListSet signature but instead of int I want to use large int. Is there any way to fix this?

Thank you, awaiting for your answer .

Answer 1

You can use the ListSetFn functor. From the documentation, you will find:

functor ListSetFn (ORD_KEY) : ORD_SET

This says that ListSetFn is a functor that takes a structure satisfying the ORD_KEY signature, which you can find in the documentation as:

type ord_key
val compare : (ord_key * ord_key) -> order 

So basically, you need to create a structure that satisfies the ORD_KEY signature, such as:

structure LargeIntKey : ORD_KEY = 
struct 
  type ord_key = LargeInt.int 
  val compare = LargeInt.compare
end

And then you can create a LargeInt instance of the ListSetFn functor by doing:

 structure LargeIntSet = ListSetFn(LargeIntKey)