task(fn, @key args, suspended, name = void, group)
Create and return a new task. The function fn is called in this task concurrently with the task that created it.
If specified, args must be a list of objects. This list will be passed to fn as its arguments.
Fn should take as many arguments as there are elements in args.
The default value of args is false, which means
no arguments will be passed to fn.
If suspended is true the task is created in the suspended
state. It can be started later by calling the task_run function.
If provided, name and group will identify the task's name and the group it belongs to.
task(^() letfn loop (i = 10)
{ showln(i)
task_sleep(2)
loop(i + 1) })
//> 10
11
12
13
14
15
16
...
// passing arguments to the function executed by a task:
function show_range(start, end)
letfn loop (i = start)
when (i < end)
{ showln(i)
task_sleep(2)
loop(i+1) }
task(show_range, args = [10, 15])
//> 10
11
12
13
14
/*
Simple tasks that don't need arguments can be started by the spawn (!) operator.
The expression that follow the operator will be evaluated in a new task.
As an example, consider the following network server which just "echoes" the message sent by
its client. It handles each client in a separate task. The client-handling logic is contained in
the expression that follows the spawn (!) operator:
*/
let s = tcp_server_stream(2020)
function echo(client)
{ showln(stream = client, read_line(client))
flush_writer(client) }
letfn loop (client = read(s))
{ !call_with_stream(client, echo)
loop(read(s)) }
// The following code can be used to test the echo server:
let c = tcp_client_stream("localhost:2020")
showln(stream = c, "hello")
flush_writer(c)
read_line(c)
//> hello