q.Recv and q.RecvE

Channel receive with a bubble on close — the comma-ok pattern specialised to v, ok := <-ch.

Signatures

func Recv[T any](ch <-chan T) T
func RecvE[T any](ch <-chan T) OkResult[T]

var ErrChanClosed = errors.New("q: channel closed")

Bare q.Recv bubbles q.ErrChanClosed. q.RecvE shares the OkResult type with q.OkE, so the chain vocabulary is identical.

What q.Recv does

msg := q.Recv(ch)

rewrites to:

msg, _qOk1 := <-(ch)
if !_qOk1 {
    return /* zeros */, q.ErrChanClosed
}

The channel expression is parenthesised so internal operators bind correctly under the leading <-.

Chain methods on q.RecvE

Same as q.OkE — Err / ErrF / Wrap / Wrapf / Catch with errors.New and fmt.Errorf without %w (there is no captured source error on a closed channel).

msg := q.RecvE(inbox).Wrap("reading inbox")
msg := q.RecvE(inbox).Err(ErrPipelineClosed)
msg := q.RecvE(inbox).Catch(func() (Msg, error) { return Msg{sentinel: true}, nil })

Statement forms

Same five positions as q.Try.

See also

• q.Ok — the general comma-ok shape this specialises.
• q.As — the type-assertion cousin.