clojure.core.async/put!

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Type: function Added: Clojure unknown Examples: 2 Runnable: 0

([port val] [port val fn1] [port val fn1 on-caller?])

Asynchronously puts a val into port, calling fn1 (if supplied) when complete, passing false iff port is already closed. nil values are not allowed. If on-caller? (default true) is true, and the put is immediately accepted, will call fn1 on calling thread.

fn1 may be run in a fixed-size dispatch thread pool and should not perform blocking IO, including core.async blocking ops (those that end in !!).

Returns true unless port is already closed.

Examples

by runexec on 2014-10-01 . May have evaluation errors. ▶

(def c (chan 1)) #'user/c (take! c (fn [x] (println "Clojure callback value " x))) nil (put! c "XYZ") ; return true unless the channel is closed. Clojure callback value XYZ true (put! c "XYZ") true

by tomdl89 on 2024-01-22 . May have evaluation errors. ▶

;; There is a maximum queue size of 1024 (def foo-chan (chan)) (dotimes [x 1025] (put! foo-chan x)) Execution error (AssertionError) at clojure.core.async… Assert failed: No more than 1024 pending puts are allowed on a single channel. Consider using a windowed buffer…

Note by hlship

The documentation here is somewhat out of date, the real documentation for more recent versions of core.async (0.1.346.0-17112a-alpha, at the time of this note) removes the bit about throwing when the channel is closed.

Instead, put! returns true unless the port is already closed, in which case false is returned.

An exception is thrown is you attempt to put! nil.

See also

• clojure.core.async/take! (0)
• clojure.core.async/>!
• clojure.core.async/>!!

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