free_vars_lr
Term.free_vars_lr : term -> term list
Returns the set of free variables in a term, in order.
An invocation free_vars_lr ty returns a list representing the set of
type variables occurring in ty. The list will be in order of variable
occurrence when scanning the parse tree of the term from left to right.
This is usually, but need not be, the textual order when the term is
printed.
Failure
Never fails.
Example
> free_vars_lr (Term `x /\ y /\ y ==> z`);
val it = [“x”, “y”, “z”]: term list
Comments
free_vars_lr is not efficient for large terms with many free
variables. More strenuous applications should use high performance set
implementations available in the Standard ML Basis Library.
free_vars_lr can be used to build pleasing quantifier prefixes.