019 optional effect multi guard no else

// RULING 2: KORU050 (multiple when-clauses, no else) must NOT fire for an
// OPTIONAL effect branch. `! ?tick` is optional; guarding it with several
// `when` clauses and NO unguarded fallback is exactly what "optional" means —
// if no guard matches, the effect simply isn't handled, which is legal for an
// optional effect. (KORU050 still applies to required/terminal branches.)
// This is the coupled fix to Ruling 1: without it, banning the no-op else
// leaves multi-guard optional effect branches with no legal spelling.
~import std/io

~pub tor poll { x: i64 }
! ?tick i64
| done

~proc poll|zig { return .{ .done = .{} }; }

~poll(x: 1)
! tick t when t > 10 |> std/io:print.ln("big")
! tick t when t > 5 |> std/io:print.ln("mid")
| done |> std/io:print.ln("done")