Internal types

Internal types are introduced in the file pats_staexp2.sats.

• S2Eapp - an application term.
• S2Ecst - a type constant (for instance, int, bool, list, etc.)
• S2Eeff - function effects.
• S2Eexi - an existentially quantified type.
• S2Eint - machine precision integer.
• S2Eintinf - infinite precision integer; commonly used for integer sorts in most compiled versions of atsopt (patsopt).
• S2Evar - a (typically universally quantified) variable.
• S2EVar - an (existentially quantified) unification variable introduced by the typechecker.