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free_varsl                                                      (Term)
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free_varsl : term list -> term list

SYNOPSIS
Returns the set of free variables in a list of terms.

KEYWORDS
variable, term.

DESCRIBE
An invocation {free_varsl [t1,...,tn]} returns a list representing
the set of free term variables occurring in {t1,...,tn}.

FAILURE
Never fails.

EXAMPLE

- free_varsl [Term `x /\ y /\ y ==> x`,
              Term `!x. x ==> p ==> y`];
> val it = [`x`, `y`, `p`] : term list




COMMENTS
Code should not depend on how elements are arranged in the
result of {free_varsl}.

{free_varsl} is not efficient for large terms with many free variables.
Demanding applications should be coded with {FVL}.



SEEALSO
Term.FVL, Term.free_vars_lr, Term.free_vars, Term.empty_varset,
Type.type_vars.

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