machines 0.2.4 → 0.2.5

raw patch · 3 files changed

+51/−1 lines, 3 files

Files

• CHANGELOG.markdown +8/−0
• machines.cabal +1/−1
• src/Data/Machine/Type.hs +42/−0

@@ -1,3 +1,11 @@+0.2.5+-----+* Added `deconstruct`, `tagDone` and `finishWith`++0.2.4+-----+* Added `asPats`, `sinkPart_`, `autoM`, and `fitM`+ 0.2.1 ----- * Fixed the `Mealy` Monad

@@ -1,6 +1,6 @@ name:          machines category:      Control, Enumerator-version:       0.2.4+version:       0.2.5 license:       BSD3 cabal-version: >= 1.10 license-file:  LICENSE

@@ -30,6 +30,11 @@   , before --  , sink +  -- ** Deconstructing machines back into plans+  , deconstruct+  , tagDone+  , finishWith+   -- * Reshaping machines   , fit   , fitM@@ -225,6 +230,43 @@ -- | This is a stopped 'Machine' stopped :: Machine k b stopped = encased Stop++--------------------------------------------------------------------------------+-- Deconstruction+--------------------------------------------------------------------------------++--- | Convert a 'Machine' back into a 'Plan'. The first value the+--- machine yields that is tagged with the 'Left' data constructor is+--- used as the return value of the resultant 'Plan'. Machine-yielded+--- values tagged with 'Right' are yielded -- sans tag -- by the+--- result 'Plan'. This may be used when monadic binding of results is+--- required.+deconstruct :: Monad m => MachineT m k (Either a o) -> PlanT k o m a+deconstruct m = PlanT $ \r y a f -> +  let aux k = runPlanT (deconstruct k) r y a f+  in runMachineT m >>= \v -> case v of+       Stop -> f+       Yield (Left o) _ -> r o+       Yield (Right o) k -> y o (aux k)+       Await g fk h -> a (aux . g) fk (aux h)++-- | Use a predicate to mark a yielded value as the terminal value of+-- this 'Machine'. This is useful in combination with 'deconstruct' to+-- combine 'Plan's.+tagDone :: Monad m => (o -> Bool) -> MachineT m k o -> MachineT m k (Either o o)+tagDone f = fmap aux+  where aux x = if f x then Left x else Right x++-- | Use a function to produce and mark a yielded value as the+-- terminal value of a 'Machine'. All yielded values for which the+-- given function returns 'Nothing' are yielded down the pipeline, but+-- the first value for which the function returns a 'Just' value will+-- be returned by a 'Plan' created via 'deconstruct'.+finishWith :: Monad m+           => (o -> Maybe r) -> MachineT m k o -> MachineT m k (Either r o)+finishWith f = fmap aux+  where aux x = maybe (Right x) Left $ f x+  ------------------------------------------------------------------------------- -- Sink