[ Non-logical Variables, Arrays, Bags, Shelves and Stores | Reference Manual | Alphabetic Index ]

store_contains(+StoreHandle, ++Key)

Check for an entry in a store object
A store handle or store name
A ground term


This checks whether a given store object contains an entry for a given key. If so, the predicate succeeds, otherwise it fails.

The key can be arbitrarily complex, but must be a ground term.

The complexity of this operation is linear in the size of the key, since the key needs to be compared. For indexing purposes, a hash value is computed from the key, and the full depth of the key is taken into account.

Note: If StoreHandle is not a handle, then it must be an atom or a compound term, and the store is identified by this term's toplevel functor together with the context module.

Modes and Determinism


This predicate is sensitive to its module context (tool predicate, see @/2).

Fail Conditions

The store does not contain an entry for Key


(4) instantiation fault
StoreHandle is uninstantiated
(4) instantiation fault
Key is not ground
(5) type error
StoreHandle is neither atom nor compound term nor store handle
(45) named object does not exist
StoreHandle is not the name of a store


    ?- store_create(Handle),
       store_set(Handle, tom, 12345),
       store_contains(Handle, tom).

    Yes (0.00s cpu)

    ?- store_create(Handle),
       store_set(Handle, tom, 12345),
       store_contains(Handle, harry).

    No (0.00s cpu)

See Also

store / 1, store_create / 1, store_count / 2, store_get / 3, store_inc / 2, store_insert / 3, store_remove / 3, store_test_and_set / 4, store_update / 4