The light-weight type of a lock, i.e. a construction which may be used to guarantee that a section will not be interrupted by another thread.

This light-weight type is independent of the underlying locking mechanism and can be used if you do not know whether your code will run with vmthreads, Posix threads, coThreads, etc.

Create a lock from a pair of locking/unlocking functions

• parameter enter

  Enter critical section.

• parameter leave

  Leave critical section. .

A lock which does nothing.

synchronize locker f returns a function f' which behaves as f but whose executions are protected by one lock obtained from locker. The same lock will be reused for all subsequent uses of f'.

For instance, synchronize Mutex.make f is a new function whose executions will by synchronized by a new lock. Conversely, synchronize (const my_lock) f is a new function whose executions will be synchronized by an existing lock my_lock.

Specialized version of synchronized.

sync lock f behaves as synchronize (const lock) f but slightly faster

Compose two lock systems into a third lock system.

A signature for modules which implement locking.