One killer feature for channels over queues is the ability to wait on many channels at the same time (like a socket select). This is done with`alts!!` (ordinary threads) or`alts!` in go blocks.

We can create a background thread with alts that combines inputs on either of two channels.`alts!!` takes a set of operations to perform - either a channel to take from or a[channel value] to put and returns the value (nil for put) and channel that succeeded:

We can create a background thread with alts that combines inputs on either of two channels.`alts!!` takes a set of operations to perform - either a channel to take from or a channel value to put and returns the value (nil for put) and channel that succeeded:

(let [c1 (a/chan)

<p>Instead of the explicit thread and blocking call, we use a go block for the producer. The consumer uses a go block to take, then returns a result channel, from which we do a blocking take.</p>

<p>== Alts</p>

<p>One killer feature for channels over queues is the ability to wait on many channels at the same time (like a socket select). This is done with<code>alts!!</code> (ordinary threads) or<code>alts!</code> in go blocks.</p>

<p>We can create a background thread with alts that combines inputs on either of two channels.<code>alts!!</code> takes a set of operations to perform - either a channel to take from or a<ahref="channel value">channel value</a> to put and returns the value (nil for put) and channel that succeeded:</p>

<p>We can create a background thread with alts that combines inputs on either of two channels.<code>alts!!</code> takes a set of operations to perform - either a channel to take from or a channel value to put and returns the value (nil for put) and channel that succeeded:</p>

<pre><codeclass="language-clojure">(let [c1 (a/chan)

c2 (a/chan)]

(a/thread (while true