Actually it is not uncommon to see 0, 1 and -1 defined as built-in primitives. The benefit is that in some interpretation schemes (bytecode, DTC) it is either f

Actually it is not uncommon to see 0, 1 and -1 defined as built-in primitives. The benefit is that in some interpretation schemes (bytecode, DTC) it is either faster or smaller, sometimes both. It also allows to ' 0 ("tick" zero, that is get the address of the next word, which in this case is some primitive zero) to pass it as a "function pointer" to another function/definition/word.