Julia has a built-in system for running tasks, which are, in general, known as coroutines. With this, a computation that generates values into a Channel (with a put! function) can be suspended as a task, while a consumer task can pick up the values (with a take! function). This is similar to the yield keyword in Python.
As a concrete example, let's take a look at a fib_producer function that calculates the first 10 Fibonacci numbers (refer to the Recursive functions section in Chapter 3, Functions), but it doesn't return the numbers, it produces them:
# code in Chapter 4\tasks.jl
function fib_producer(c::Channel)
a, b = (0, 1)
for i = 1:10
put!(c, b)
a, b = (b, a + b)
end
end Construct a Channel by providing this function as an argument:
chnl = Channel(fib_producer)
The task's state is now runnable. To get the Fibonacci numbers, start consuming them with take! until Channel is closed, and the task is finished (state is :done...