// Failable `or` chains (ERR step E2.4b). `lhs or rhs` with failable operands
// is a left-to-right, short-circuit chain: each failing attempt routes to the
// next operand; the chain resolves when an operand succeeds (or a value
// terminator absorbs). `try` marks an operand whose failure is visible routing
// (path-marker rule); a bare failable operand is allowed when a downstream
// terminator absorbs it. A `catch` over a parenthesized chain redirects the
// chain's total failure to the handler instead of the function. Absorbed
// failures clear the trace buffer; `onfail` does not fire for a failure that
// never leaves its block. This run takes only absorbed paths → exit 120.

#import "modules/std.sx";

E :: error { A, B };

fa :: (n: i32) -> (i32, !E) {
    if n == 0 { raise error.A; }
    if n < 0  { raise error.B; }
    return n;
}

fv :: (n: i32) -> !E {                       // void (pure) failable
    if n == 0 { raise error.A; }
    return;
}

main :: () -> (i32, !E) {
    onfail print("onfail fired (BUG)\n");    // must NOT fire — every chain below absorbs

    r : i32 = 0;
    r = r + (try fa(0) or try fa(7));               // a fails → b succeeds → 7
    r = r + (try fa(0) or try fa(0) or try fa(3));   // first two fail → third → +3  = 10
    r = r + (fa(0) or fa(0) or 96);                  // bare chain + value terminator → +96 = 106
    r = r + ((try fa(0) or try fa(0)) catch (e) 5);    // both fail → catch handler → +5  = 111
    r = r + ((try fa(0) or try fa(9)) catch (e) 0);    // second succeeds → catch skipped → +9 = 120

    try fv(0) or try fv(1);                          // void chain: first fails → second succeeds

    return r;                                         // success → exit 120; onfail skipped
}