# a small illustration about how to use PF tasks

# the word to use is 'fork'. when this word occurs in PF code, a new
# task is created. fork takes a single number as an argument. this
# number signifies how many atoms are passed from the datastack to the
# new task.

# the word 'fork' will fork off a new task. this means that at the
# moment the word is encountered, two roads are taken: a parent road
# and a client road.

# PARENT

# from the parent side '1 fork' takes one argument of the stack and
# returns. similarly '2 fork' takes 2 arguments and returns.

# CHILD

# from the child side, '1 fork' does the opposite: it will leave only
# a single atom on the data stack, and will continue running. '2 fork'
# will leave 2, etc..

# for instance: suppose before '1 fork' is called, the data stack
# contains 3 number elements:

#   <3> 100 200 300

# after '1 fork', the parent's data stack will look like:
#   <2> 100 200
# and the code following the 'fork' word is not executed.

# while the child data stack will look like
#   <1> 300
# with the code following the 'fork' code executed.

# so 'fork' splits a data stack in 2 pieces, and gives the top piece
# to the client task, and returns the remaining piece to the parent.



load-scheduler

: fork-demo
	1 fork	# give one argument to the client task and return

	# client will continue here with the single argument
	begin
		dup p cr	# print the atom we got while being created
		1000. sleep	# sleep for a bit
	again ;


"type '123 fork-demo' to start a single demo task task." p cr

interactive