Safe Haskell	Safe-Inferred
Language	Haskell2010

Acquire

Contents

IO
Acquire
Use

Synopsis

acquireAndUse :: Acquire env -> Use env err res -> IO (Either err res)
useAcquired :: env -> Use env err res -> IO (Either err res)
newtype Acquire env = Acquire (IO (env, IO ()))
startAndStop :: IO a -> (a -> IO ()) -> Acquire a
newtype Use env err res = Use (ReaderT env (ExceptT err IO) res)
mapEnv :: (b -> a) -> Use a err res -> Use b err res
mapErr :: (a -> b) -> Use env a res -> Use env b res
mapEnvAndErr :: (envB -> envA) -> (errA -> errB) -> Use envA errA res -> Use envB errB res

IO

acquireAndUse :: Acquire env -> Use env err res -> IO (Either err res) Source #

Execute an action, which uses a resource, having a resource provider.

useAcquired :: env -> Use env err res -> IO (Either err res) Source #

Run use on an acquired environment.

Acquire

newtype Acquire env Source #

Resource provider. Abstracts over resource acquisition and releasing.

Composes well, allowing you to merge multiple providers into one.

Implementation of http://www.haskellforall.com/2013/06/the-resource-applicative.html

Constructors

Acquire (IO (env, IO ()))

Instances

Instances details

MonadIO Acquire Source #
Instance details Defined in Acquire Methods liftIO :: IO a -> Acquire a #
Applicative Acquire Source #
Instance details Defined in Acquire Methods pure :: a -> Acquire a # (<>) :: Acquire (a -> b) -> Acquire a -> Acquire b # liftA2 :: (a -> b -> c) -> Acquire a -> Acquire b -> Acquire c # (>) :: Acquire a -> Acquire b -> Acquire b # (<*) :: Acquire a -> Acquire b -> Acquire a #
Functor Acquire Source #
Instance details Defined in Acquire Methods fmap :: (a -> b) -> Acquire a -> Acquire b # (<$) :: a -> Acquire b -> Acquire a #
Monad Acquire Source #
Instance details Defined in Acquire Methods (>>=) :: Acquire a -> (a -> Acquire b) -> Acquire b # (>>) :: Acquire a -> Acquire b -> Acquire b # return :: a -> Acquire a #

startAndStop Source #

Arguments

:: IO a	Start the service.
-> (a -> IO ())	Stop the service.
-> Acquire a

Construct Acquire by specifying a resource initializer and finalizer actions.

Use

newtype Use env err res Source #

Resource handler, which has a notion of pure errors.

Constructors

Use (ReaderT env (ExceptT err IO) res)

Instances

Instances details

MonadError err (Use env err) Source #
Instance details Defined in Acquire Methods throwError :: err -> Use env err a # catchError :: Use env err a -> (err -> Use env err a) -> Use env err a #
MonadReader env (Use env err) Source #
Instance details Defined in Acquire Methods ask :: Use env err env # local :: (env -> env) -> Use env err a -> Use env err a # reader :: (env -> a) -> Use env err a #
Bifunctor (Use env) Source #
Instance details Defined in Acquire Methods bimap :: (a -> b) -> (c -> d) -> Use env a c -> Use env b d # first :: (a -> b) -> Use env a c -> Use env b c # second :: (b -> c) -> Use env a b -> Use env a c #
MonadIO (Use env err) Source #
Instance details Defined in Acquire Methods liftIO :: IO a -> Use env err a #
Monoid err => Alternative (Use env err) Source #
Instance details Defined in Acquire Methods empty :: Use env err a # (<\|>) :: Use env err a -> Use env err a -> Use env err a # some :: Use env err a -> Use env err [a] # many :: Use env err a -> Use env err [a] #
Applicative (Use env err) Source #
Instance details Defined in Acquire Methods pure :: a -> Use env err a # (<>) :: Use env err (a -> b) -> Use env err a -> Use env err b # liftA2 :: (a -> b -> c) -> Use env err a -> Use env err b -> Use env err c # (>) :: Use env err a -> Use env err b -> Use env err b # (<*) :: Use env err a -> Use env err b -> Use env err a #
Functor (Use env err) Source #
Instance details Defined in Acquire Methods fmap :: (a -> b) -> Use env err a -> Use env err b # (<$) :: a -> Use env err b -> Use env err a #
Monad (Use env err) Source #
Instance details Defined in Acquire Methods (>>=) :: Use env err a -> (a -> Use env err b) -> Use env err b # (>>) :: Use env err a -> Use env err b -> Use env err b # return :: a -> Use env err a #
Monoid err => MonadPlus (Use env err) Source #
Instance details Defined in Acquire Methods mzero :: Use env err a # mplus :: Use env err a -> Use env err a -> Use env err a #

mapEnv :: (b -> a) -> Use a err res -> Use b err res Source #

Map the environment of a resource handler.

mapErr :: (a -> b) -> Use env a res -> Use env b res Source #

Map the error of a resource handler.

mapEnvAndErr :: (envB -> envA) -> (errA -> errB) -> Use envA errA res -> Use envB errB res Source #

Map both the environment and the error of a resource handler.