Concurrency. #

Cyber supports fibers as a concurrency mechanism. There are plans to support preemptive concurrency with async/await as well as multithreading.

Fibers. #

Fibers in Cyber allow representing execution contexts as first-class values. They contain their own call stack and program counters. Fibers by themselves do not enable parallelism.

The coinit creates a new fiber from a function call syntax. Using coyield inside a function pauses the current fiber and execution is returned to the fiber that invoked coresume.

var count = 0

var foo = func ():
  count += 1
  coyield
  count += 1

var fiber = coinit foo()
print count          -- '0'
coresume fiber
print count          -- '1'
coresume fiber
print count          -- '2'

In Cyber, coyield can be used anywhere in a fiber’s call stack.

func foo():
  print 'foo'
  bar()

func bar():
  -- Nested coyield in call stack.
  coyield
  print 'bar'

var fiber = coinit foo()
coresume fiber

coresume also returns the resulting value.

func foo():
  return 123

var fiber = coinit foo()
print(coresume fiber)    -- '123'

coyield can return a value back to coresume.

Planned Feature

Use Fiber.status() to get the current state of the fiber.

func foo():
  coyield
  print 'done'

var fiber = coinit foo()
print fiber.status()   -- '.paused'
coresume fiber
print fiber.status()   -- '.paused'
coresume fiber
print fiber.status()   -- '.done'

The main execution context is a fiber as well. Once the main fiber has finished, the VM is done and control is returned to the host.

Gas mileage. #

Planned Feature

Async. #

Planned Feature

Multi-thread. #

Planned Feature