MVar
Related Docs:
object MVar
| package concurrent
Check whether the MVar is empty.
Check whether the MVar is empty.
Notice that the boolean value returned is just a snapshot of the state of
the MVar. By the time you get to react on its result, the MVar may have
been filled (or emptied) - so be extremely careful when using this
operation. Use tryTake instead if possible.
A slight variation on update that allows a value to be returned (b) in
addition to the modified value of the MVar.
Put a value into an MVar.
Put a value into an MVar. If the MVar is currently full, put will
wait until it becomes empty.
Atomically read the contents of an MVar.
Atomically read the contents of an MVar. If the MVar is currently
empty, read will wait until it is full. read is guaranteed to receive
the next put.
Take a value from an MVar, put a new value into the MVar and return the
value taken.
Return the contents of the MVar.
Return the contents of the MVar. If the MVar is currently empty, take
will wait until it is full. After a take, the MVar is left empty.
A non-blocking version of put.
A non-blocking version of put. The tryPut function attempts to put the
value x into the MVar, returning true if it was successful, or
false otherwise.
A non-blocking version of read.
A non-blocking version of read. The tryRead function returns
immediately, with None if the MVar was empty, or Some(x) if the
MVar was full with contents x.
A non-blocking version of take.
A non-blocking version of take. The tryTake action returns immediately,
with None if the MVar was empty, or Some(x) if the MVar was full
with contents x. After tryTake, the MVar is left empty.
Replaces the contents of an MVar with the result of f(a).
An
MVar[A]is a mutable location that is either empty or contains a value of typeA. It has two fundamental operations:putwhich fills anMVarif it is empty and blocks otherwise, andtakewhich empties anMVarif it is full and blocks otherwise. They can be used in multiple different ways:takeandputasreceiveandsend, andMVar[Unit], withtakeandputaswaitandsignal.They were introduced in the paper "Concurrent Haskell" by Simon Peyton Jones, Andrew Gordon and Sigbjorn Finne.