Compat.tyvars : term -> type list

SYNOPSIS
Returns a list of the type variables free in a term.

DESCRIBE

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.

FAILURE
Never fails. The function is not accessible unless the hol88 library has been loaded.

EXAMPLE
  - 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

COMMENTS
tyvars does not appear in hol90; use type_vars_in_term instead. WARNING: the order of the list returned from tyvars need not be the same as that returned from type_vars_in_term.

In the current HOL logic, there is no binding operation for types, so `is free in' is synonymous with `appears in'.

SEEALSO  tyvarsl

HOL  Kananaskis 0