// First runnable `try` (ERR step E1.4a). The STANDALONE form: a failable
// expression whose failure propagates to the enclosing function's error
// return (Zig-style). `outer` calls `try inner(n)` — on `inner`'s failure
// `outer` returns that error; on success it continues. Both are pure
// failable (`-> !E`). The error-channel tuple ABI for value-carrying
// `-> (T, !)` and `try` in an `or` chain land in ERR E1.4b/E2.

#import "modules/std.sx";

E :: error { Bad, Worse }

inner :: (n: s32) -> !E {
    if n < 0 { raise error.Bad; }
    return;                              // success — no error
}

// Propagates inner's error (standalone `try`, target = function return).
outer :: (n: s32) -> !E {
    try inner(n);
    return;
}

main :: () -> s32 {
    bad  := outer(-1);                   // inner raises Bad -> outer propagates
    good := outer(7);                    // inner succeeds   -> outer succeeds
    r : s32 = 0;
    if bad  == error.Bad   { r = r + 5; }    // true  -> +5
    if good == error.Bad   { r = r + 1; }     // false (success = no error)
    if bad  == error.Worse { r = r + 2; }     // false (propagated Bad)
    print("try result: {}\n", r);             // -> 5
    return r;
}