@assert

The @assert directive is also invaluable for debugging and validating invariants in your code.

Examples

It is invoked with an expression argument and optional string message:

@assert 2 + 2 == 4

@assert 1, "cannot fail!"

Assertions support lazy evaluation. That means you can write assertions that reference labels that are defined later in your code:

@assert SubRoutine.length == 4

SubRoutine:
    nop
    nop
    nop
    rts
    @defn .length, @here - SubRoutine