-->op Type.--> : hol_type * hol_type -> hol_type
Right associative infix operator for building a function type.
If ty1 and ty2 are HOL types, then
ty1 --> ty2 builds the HOL type
ty1 -> ty2.
Never fails.
> bool --> alpha;
val it = “:bool -> α”: hol_type
This operator associates to the right, that is,
ty1 --> ty2 --> ty3 is identical to
ty1 --> (ty2 --> ty3).
Type.dom_rng, Type.mk_type, Type.mk_thy_type