Takes the topmost item from the stack and pushes 1 to the stack if the key is present, 0 if it is not.

Input stack: key

Output stack: 0 or 1

This is the primary way of testing presence of a key in the database. Only valid within WRITE's or READ's scopes.

This example demonstrates testing of the key presence both within READ and WRITE transaction scopes:

PumpkinDB> ["hi" "there" ASSOC "hi" ASSOC? COMMIT] WRITE ["hello" ASSOC?] READ
0x01 0x00

Because hello key was not associated (only hi was), the second boolean value is 0x00 (false).




EmptyStack error if there are less than two items on the stack

NoTransaction error if there's no current read or write transaction


present : "hi" DUP "there" [ASSOC COMMIT] WRITE [ASSOC?] READ.
not_present : "hi" "there" [ASSOC COMMIT] WRITE "bye" [ASSOC?] READ NOT.
assocp_requires_txn : [0 ASSOC?] TRY UNWRAP 0x08 EQUAL?.
assoc_requires_one_item : [[ASSOC] WRITE] TRY UNWRAP 0x04 EQUAL?.

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