Compat.tyvars : term -> type list
Found in the hol88 library. When applied to a term, tyvars returns a list (possibly empty) of the type variables which are free in the term.
- theorem "pair" "PAIR"; |- !x. (FST x,SND x) = x - Compat.tyvars (concl PAIR); val it = [(==`:'b`==),(==`:'a`==)] : hol_type list - Compat.tyvars (--`x + 1 = SUC x`--); [] : hol_type list
In the current HOL logic, there is no binding operation for types, so `is free in' is synonymous with `appears in'.