Eta

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std.actor

<- Stdlib Reference | Language Guide | Detailed reference

BEAM-like local actor runtime wrappers over %actor-* primitives.

(import std.actor)

Use std.actor for local PID and VM-mailbox messaging: spawn, send, selective receive, links, monitors, exit signals, local registration, and process introspection. Use std.actor.node for distributed actor-node links and std.net for transport-level NNG sockets.

SymbolDescription
(self)Return the current actor PID.
(pid? x)Return #t when x is a PID value.
(alive? pid)Return #t when pid is still alive in the local actor system.
(spawn thunk)Spawn a new actor running zero-argument thunk; returns PID.
(send pid payload)Send one message to pid; returns payload on success or #f.
(send/checked pid payload)Send with delivery status: 'ok, 'no-process, 'no-route, or 'transport-error.
(! pid payload)Alias for send.
(trap-exit! enabled?)Enable or disable trap-exit mode for the current actor.
(link pid)Link the current actor with pid.
(unlink pid)Remove a link to pid.
(monitor pid)Monitor pid; returns a monitor reference.
(demonitor ref [flush?])Remove monitor ref; optional flush? removes queued DOWN for that ref.
(exit pid reason)Send an exit signal with reason to pid.
(kill pid)Send an untrappable kill signal to pid.
(register name pid)Register local name to resolve to pid.
(unregister name)Remove one local registration.
(whereis name)Resolve local registered name to PID or #f.
(registered)Return all registered local names.
(process-info pid [key])Return process info alist or one keyed value ('pid, 'state, 'last-yield-reason, 'message-queue-len, 'registered-name, 'links, 'monitors, 'reductions). state is one of 'runnable, 'running, 'waiting, 'exited. last-yield-reason is one of 'none, 'budget-exhausted, 'blocked-on-receive, 'finished, 'error.
(match-case matcher handler)Build one receive clause for receive-match.
(match-list head [arity])Match list messages by head value and optional tail arity.
(match-symbol sym)Match one symbol message by eq?.
(match-predicate pred)Lift predicate pred into a receive matcher.
(receive cases [timeout-ms [timeout-thunk]])Selective receive with a clause list and optional timeout handler thunk.
(receive-match matcher-or-cases . rest)Receive by predicate or clause list; optional timeout and timeout thunk.
(receive-after timeout-ms)Receive one message with timeout; returns #f on timeout.
(mailbox-length)Return queued message count for the current actor.

Scheduler runtime controls:

case is a language keyword in Eta, so the clause constructor is named match-case.

Trap-exit and monitor message shapes:

'(EXIT from-pid reason)
'(DOWN ref process pid reason)

(receive
  (list
    (match-case (match-list 'ping 1)
                (lambda (msg) (send (car (cdr msg)) 'pong)))
    (match-case (match-predicate number?)
                (lambda (n) (* n 2))))
  1000
  (lambda () 'timeout))

Source: stdlib/std/actor.eta