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| Control.Concurrent.SampleVar | | Portability | non-portable (concurrency) | | Stability | experimental | | Maintainer | libraries@haskell.org |
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| Description |
| Sample variables
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| Synopsis |
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| Sample Variables |
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| type SampleVar a = MVar (Int, MVar a) |
Sample variables are slightly different from a normal MVar:
- Reading an empty SampleVar causes the reader to block.
(same as takeMVar on empty MVar)
- Reading a filled SampleVar empties it and returns value.
(same as takeMVar)
- Writing to an empty SampleVar fills it with a value, and
potentially, wakes up a blocked reader (same as for putMVar on
empty MVar).
- Writing to a filled SampleVar overwrites the current value.
(different from putMVar on full MVar.)
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| newEmptySampleVar :: IO (SampleVar a) |
| Build a new, empty, SampleVar |
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| newSampleVar :: a -> IO (SampleVar a) |
| Build a SampleVar with an initial value. |
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| emptySampleVar :: SampleVar a -> IO () |
| If the SampleVar is full, leave it empty. Otherwise, do nothing. |
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| readSampleVar :: SampleVar a -> IO a |
| Wait for a value to become available, then take it and return. |
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| writeSampleVar :: SampleVar a -> a -> IO () |
| Write a value into the SampleVar, overwriting any previous value that
was there. |
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| Produced by Haddock version 0.6 |
