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retract_in
Entity: predicate
retractall
Entity: predicate
Usage:
retract(Clause)
Retracts the first clause which is unifiable with Clause .
| Clause | the clause to retract. |
Fails if there is no clause which is unifiable with Clause .
Usage:
retract_in(Clause)
Retracts the first clause which is unifiable with Clause both
in the run-time database (like retract) and in the text file containing
the running program.
| Clause | the clause to retract. |
Fails if there is no clause which is unifiable with Clause.
Usage:
retractall(Clause)
Retracts all clauses which are unifiable with Clause .
| Clause | the clause to retract. |
Succeeds always.
Example:
?-retract_in(test(X)), write(X), nl, !, test(Y), write(Y), nl, fail.
test(1).
test(2).
test(3).
Run this example four times (press four times F5 ).
See also:
