What is the S.md

What is the s?

The s essentially represents the context, and is like the s of ST.

It's used to distinguish between closed and open terms:

• Closed term: type ClosedTerm = forall s. Term s a
• Arbitrary term: exists s. Term s a
• NB: (exists s. Term s a) -> b is isomorphic to
• forall s. Term s a -> b