| Safe Haskell | Safe-Inferred |
|---|---|
| Language | Haskell2010 |
Data.Monoid.Synchronisation
Synopsis
- newtype FirstToFinish m a = FirstToFinish {
- runFirstToFinish ∷ m a
- newtype LastToFinish m a = LastToFinish {
- runLastToFinish ∷ m a
- firstToLast ∷ FirstToFinish m a → LastToFinish m a
- lastToFirst ∷ LastToFinish m a → FirstToFinish m a
- newtype LastToFinishM m a = LastToFinishM {
- runLastToFinishM ∷ m a
- firstToLastM ∷ FirstToFinish m a → LastToFinishM m a
- lastToFirstM ∷ LastToFinishM m a → FirstToFinish m a
Documentation
newtype FirstToFinish m a Source #
First-to-finish synchronisation. Like Alt it is a monoid under <|>.
First-to-finish is the additive monoid of
near-semiring for which
multiplication is given by LastToFinish.
-- | Return first available value.
--
readFirstMVar :: [TMVar a] -> STM a
readFirstMVar = runFirstToFinish
. foldMap (FirstToFinish . readTMVar)Constructors
| FirstToFinish | |
Fields
| |
Instances
newtype LastToFinish m a Source #
Last-to-finish synchronisation. It is the multiplicative semigroup of
the near-semiring for which addition is
given by FirstToFinish.
This is similar to Ap (see LastToFinishM) in the sense that it will wait
for all monadic effects, but unlike Ap it will not combine all results
using a monoid instance, but rather it will return the last one. Also unlike
Ap it does not have a monoidal unit.
-- | Read all 'TMVar's and return the one that was filled last.
--
readAllTMVars :: Monoid a => NonEmpty (TMVar a) -> STM a
readAllTMVars = runLastToFinish
. foldMap1 (LastToFinish . readTMVar)
-- from 'semigroupoids' package or use 'foldr1' and 'fmap'
-- from 'base'Constructors
| LastToFinish | |
Fields
| |
Instances
firstToLast ∷ FirstToFinish m a → LastToFinish m a Source #
lastToFirst ∷ LastToFinish m a → FirstToFinish m a Source #
newtype LastToFinishM m a Source #
Last-to-finish synchronisation. Like Ap it is a monoid under <*>.
The advantage over LastToFinish is that it has a Monoid instance, but
a must be a Monoid as well. LastToFinishM and FirstToFinish form
a unitial near-ring when m ~ STM.
-- | Read all 'TMVar's and combine the result using 'Monoid' instance.
--
readAllTMVars :: Monoid a => [TMVar a] -> STM a
readAllTMVars = runLastToFinish
. foldMap (LastToFinish . readTMVar)Constructors
| LastToFinishM | |
Fields
| |
Instances
firstToLastM ∷ FirstToFinish m a → LastToFinishM m a Source #
lastToFirstM ∷ LastToFinishM m a → FirstToFinish m a Source #