Returns a list of the type variables free in a list of terms.
DESCRIBE
Found in the hol88 library. When applied to a list of terms, tyvarsl
returns a list (possibly empty) of the type variables which are free in
any of those terms.
FAILURE
Never fails. The function is not accessible unless the hol88 library has
been loaded.
EXAMPLE
- tyvarsl [--`!x. x = 1`--, --`!x:'a. x = x`--];
[(==`:'a`==)] : hol_type list
USES
Finding all the free type variables in the assumptions of a theorem, as a check
on the validity of certain inferences.
COMMENTS
tyvarsl does not appear in hol90. In the current HOL logic, there is no
binding operation for types, so `is free in' is synonymous with `appears in'.