bux-lang/examples/macro_repeat.bux

// Macro repetition $(…)* + fragment kinds expr/ident/tt (session 61)
import Std::Io::{PrintLine};
import Std::String::{String_FromInt};

// Sum any number of int exprs
// Template body is a single block (lets + $(…)* + result expr).
macro! sum_n {
    ( $($x:expr),* ) => {
        var __sum_acc: int = 0;
        $( __sum_acc = __sum_acc + $x; )*
        __sum_acc
    }
}

// Bind an identifier name and call it as a zero-arg func via expr wrap
// (ident fragment must be a bare identifier at the call site)
macro! call0 {
    ( $f:ident ) => {
        {
            $f()
        }
    }
}

// tt is accepted like expr (token-tree MVP)
macro! id_tt {
    ( $t:tt ) => {
        {
            $t
        }
    }
}

func FortyTwo() -> int {
    return 42;
}

func Main() -> int {
    let a: int = sum_n!(1, 2, 3);
    let b: int = sum_n!();
    let c: int = call0!(FortyTwo);
    let d: int = id_tt!(7);
    PrintLine(String_FromInt(a));
    PrintLine(String_FromInt(b));
    PrintLine(String_FromInt(c));
    PrintLine(String_FromInt(d));
    if a != 6 {
        PrintLine("FAIL sum_n 1+2+3");
        return 1;
    }
    if b != 0 {
        PrintLine("FAIL sum_n empty");
        return 1;
    }
    if c != 42 {
        PrintLine("FAIL call0 ident");
        return 1;
    }
    if d != 7 {
        PrintLine("FAIL id_tt");
        return 1;
    }
    PrintLine("PASS macro_repeat");
    return 0;
}