This library provides the inverse functionality of the built-in
numbervars/3. Note that this library suffers from the known issues that
'$VAR'(X) is a normal Prolog term and, -unlike the built-in numbervars-,
the inverse predicates do not process cyclic terms. The following
predicate is true for any acyclic term that contains no '$VAR'(X),
integer(X)
terms and no constraint variables:
always_true(X) :-
copy_term(X, X2),
numbervars(X),
varnumbers(X, Copy),
Copy =@= X2.
- See also
- - numbervars/4, =@=/2 (variant/2).
- Compatibility
- - This library was introduced by Quintus and available in
many related implementations, although not with exactly the
same set of predicates.
- numbervars(+Term) is det
- Number variables in Term using $VAR(N). Equivalent to
numbervars(Term, 0, _)
.
- See also
- - numbervars/3, numbervars/4
- varnumbers(+Term, -Copy) is det
- Inverse of numbervars/1. Equivalent to
varnumbers(Term, 0,
Copy)
.
- varnumbers(+Term, +Start, -Copy) is det
- Inverse of numbervars/3. True when Copy is a copy of Term with
all variables numbered >= Start consistently replaced by fresh
variables. Variables in Term are shared with Copy rather than
replaced by fresh variables.
- Errors
- -
domain_error(acyclic_term, Term)
if Term is cyclic.
- Compatibility
- - Quintus, SICStus. Not in YAP version of this library
- max_var_number(+Term, +Start, -Max) is det
- True when Max is the max of Start and the highest numbered
$VAR(N) term.
- author
- - Vitor Santos Costa
- Compatibility
- - YAP
- varnumbers_names(+Term, -Copy, -VariableNames) is det
- If Term is a term with numbered and named variables using the
reserved term '$VAR'(X), Copy is a copy of Term where each
'$VAR'(X) is consistently replaced by a fresh variable and
Bindings is a list
X = Var
, relating the X terms with the
variable it is mapped to.
- See also
- - numbervars/3, varnumbers/3, read_term/3 using the
variable_names
option.