Macros

Macro function and method bodies are compiled into the body of the caller function or method. Macro parameters may be evaluated zero or more times.

Macro names must be upper case to distinguish them from regular functions and methods.

Possibly allow modifying the AST in macros in the future.

macro CHECK(cond: bool, message: string):
    if not cond:
        print(message)

func not_four() -> string:
    print("Called not_four().")

    return "Not 4."

func add(a: i64, b: i64) -> i64:
    print(f"Adding {a} and {b}.")

    return a + b

class Logger:
    enabled: bool

    macro LOG(self, message: string):
        if self.enabled:
            print(message)

func main():
    logger = Logger(False)
    number = 4

    CHECK(number == 4, not_four())

    print("Logging with logger disabled.")
    logger.LOG(f"3 + 4 = {add(3, number)}")

    print("Logging with logger enabled.")
    logger.enabled = True
    logger.LOG(f"3 + 4 = {add(3, number)}")

Build and run:

❯ mys run
 ✔ Reading package configuration (0 seconds)
 ✔ Building (0.01 seconds)
Logging with logger disabled.
Logging with logger enabled.
Adding 3 and 4.
3 + 4 = 7