NONE?
Tests if the topmost stack item's length is equal to zero.
Input stack: a
Output stack: c
NONE? will push 1 if the item's length is equal to zero, 0 otherwise.
It has a "sister" instruction of SOME?. Together they allow to express a concept of an optional value.
PumpkinDB> [] NONE?
1
PumpkinDB> [1] NONE?
0
Allocation
None
Errors
EmptyStack error if there is less than one items on the stack
Tests
works : [] NONE?.
works_1 : [1] NONE? NOT.
empty_stack : [NONE?] TRY UNWRAP 0x04 EQUAL?.