use '==' consistently rather than '->' in examples

[ghc-base.git] / GHC / Conc.lhs

diff --git a/GHC/Conc.lhs b/GHC/Conc.lhs
index 715e569..ec6e064 100644 (file)
--- a/GHC/Conc.lhs
+++ b/GHC/Conc.lhs
@@ -310,7 +310,8 @@ In the paper, 'throwTo' is non-blocking; but the library implementation adopts
 a more synchronous design in which 'throwTo' does not return until the exception
 is received by the target thread.  The trade-off is discussed in Section 9 of the paper.
 Like any blocking operation, 'throwTo' is therefore interruptible (see Section 5.3 of
 a more synchronous design in which 'throwTo' does not return until the exception
 is received by the target thread.  The trade-off is discussed in Section 9 of the paper.
 Like any blocking operation, 'throwTo' is therefore interruptible (see Section 5.3 of

-the paper).
+the paper).  Unlike other interruptible operations, however, 'throwTo'
+is /always/ interruptible, even if it does not actually block.

 
 There is no guarantee that the exception will be delivered promptly,
 although the runtime will endeavour to ensure that arbitrary
 
 There is no guarantee that the exception will be delivered promptly,
 although the runtime will endeavour to ensure that arbitrary

@@ -476,6 +477,10 @@ thenSTM (STM m) k = STM ( \s ->
 returnSTM :: a -> STM a
 returnSTM x = STM (\s -> (# s, x #))
 
 returnSTM :: a -> STM a
 returnSTM x = STM (\s -> (# s, x #))
 

+instance MonadPlus STM where
+  mzero = retry
+  mplus = orElse
+

 -- | Unsafely performs IO in the STM monad.  Beware: this is a highly
 -- dangerous thing to do.  
 --
 -- | Unsafely performs IO in the STM monad.  Beware: this is a highly
 -- dangerous thing to do.  
 --