type_varsl

Type.type_varsl : hol_type list -> hol_type list

Returns the set of type variables in a list of types.

An invocation type_varsl [ty1,...,tyn] returns a list representing the set-theoretic union of the type variables occurring in ty1,...,tyn.

Failure

Never fails.

Example

- type_varsl [alpha, beta, bool, ((alpha --> beta) --> bool --> beta)];
> val it = [`:'a`, `:'b`] : hol_type list

Comments

Code should not depend on how elements are arranged in the result of type_varsl.

See also

Type.type_vars, Type.type_var_in, Type.exists_tyvar, Type.polymorphic, Term.free_vars