\DOC freesl
\TYPE {Compat.freesl : term list -> term list}
\SYNOPSIS
Returns a list of the free variables in a list of terms.
\DESCRIBE
When applied to a list of terms, {freesl} returns a list of the variables
which
are free in any of those terms. There are no repetitions in the list
produced
even if several terms contain the same free variable.
\FAILURE
Never fails.
\EXAMPLE
In the following example there are two free instances each of {x} and
{y},
whereas the only instances of {z} are bound:
{
- freesl [(--`x+y=2`--), (--`!z. z >= (x-y)`--)];
val it = [(--`x`--),(--`y`--)] : term list
}
\COMMENTS
{freesl} is not in hol90; use {free_varsl} instead. WARNING: One can not
depend on the order of the list returned by {freesl} to be identical to
that
returned by {free_varsl}. They are coded in terms of {frees} and
{free_vars},
and thus the discussion in the documentation for {frees} applies by
extension.
\SEEALSO
frees, free_in, thm_frees.
\ENDDOC