040 effect discard carveouts legal

// The KORU039 carve-outs: discards that stay legal.
//
// (1) A LONE `! row _ |> _` on a REQUIRED effect — explicit handle-and-ignore
//     carries meaning (RULING 1's carve-out, also see 220_018).
// (2) `|` outcome discards — a result must ROUTE somewhere; `| err _ |> _`
//     is the honest landing, and a guarded `| ok` arm's unguarded sibling is
//     exactly what KORU050 requires.
//
// The refusal (220_020) is only for a discard SIBLING on an effect branch
// already handled — a no-op on a per-fire filter.

~import std/io

~pub tor poll { x: i64 }
! row i64
| done
| err i64

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

~pub tor risky { x: i64 }
| ok i64
| err i64

~proc risky|zig { return .{ .ok = x }; }

~poll(x: 1)
! row _ |> _
| done |> _
| err _ |> _

~risky(x: 2)
| ok v when v > 10 |> std/io:print.ln("big")
| ok _ |> _
| err _ |> _