Send and receive through a channel

This deterministic recipe shows the fundamental channel states without relying on scheduler order.

Project tree

channels/
└── main.km

Source

import go fmt from "fmt";

function main(): void {
  const channel = goChannel[int](2);
  channel <- 21;
  channel <- 42;
  const [first, firstOpen] = <-channel;
  const second = <-channel;
  closeGoChannel(channel);
  const [afterClose, stillOpen] = <-channel;
  fmt.Println(first, firstOpen, second, afterClose, stillOpen);
}

Run

keika check main.km
keika run main.km

Expected output:

21 true 42 0 false

The buffered sends complete before a receiver starts. The first checked receive returns 21, true; the next receive returns 42. After closing and draining the channel, checked receive returns the int zero value and false.

Boundary behavior

• Sending or closing a closed channel panics as in Go.
• Receiving from a closed, drained channel returns the zero value immediately.
• A nil channel blocks for send/receive; closing it panics.
• Only a bidirectional or send-capable channel can be closed.
• select preserves Go readiness and nondeterministic selection among ready cases.

Use GoSendChannel<T> and GoReceiveChannel<T> in signatures when direction is part of the API contract.