Control.Concurrent.SVar

SVar

data SVar a

An SVar (skip variable) is a variable which allows for non-blocking updates, and blocking reads if the stored data has been read already, or if there is no data.

Creation of SVars

newEmptySVar :: IO (SVar a)

Create an empty SVar.

newSVar :: a -> IO (SVar a)

Create an SVar which contains the supplied value.

Modification of SVars

putSVar :: SVar a -> a -> IO ()

Put a value into an SVar. Never blocks, always overwrites the current value, if there is one.

readSVar :: SVar a -> IO a

Read a value from an SVar. Blocks if there isn't a new value since the last read, or if the SVar is empty.