Data.Streaming.Process

A full tutorial for this module is available at: https://github.com/snoyberg/conduit/blob/master/PROCESS.md.

Note that, while the tutorial covers Data.Conduit.Process, that module closely follows the present one, and almost all concepts in the tutorial apply here.

Functions

streamingProcess :: (MonadIO m, InputSource stdin, OutputSink stdout, OutputSink stderr) => CreateProcess -> m (stdin, stdout, stderr, StreamingProcessHandle)

The primary function for running a process. Note that, with the exception of UseProvidedHandle, the values for std_in, std_out and std_err will be ignored by this function.

Since 0.1.4

closeStreamingProcessHandle :: MonadIO m => StreamingProcessHandle -> m ()

Free any resources (e.g. Handles) acquired by a call to streamingProcess.

Since: 0.1.16

Specialized streaming types

data Inherited

Inherit the stream from the current process.

Since 0.1.4

Constructors

Inherited

Instances

OutputSink Inherited

Defined in Data.Streaming.Process

Methods

osStdStream :: (Maybe Handle -> IO Inherited, Maybe StdStream)

InputSource Inherited

Defined in Data.Streaming.Process

Methods

isStdStream :: (Maybe Handle -> IO Inherited, Maybe StdStream)

data ClosedStream

Close the stream with the child process.

You usually do not want to use this, as it will leave the corresponding file descriptor unassigned and hence available for re-use in the child process.

Since 0.1.4

Constructors

ClosedStream

Instances

OutputSink ClosedStream

Defined in Data.Streaming.Process

Methods

osStdStream :: (Maybe Handle -> IO ClosedStream, Maybe StdStream)

InputSource ClosedStream

Defined in Data.Streaming.Process

Methods

isStdStream :: (Maybe Handle -> IO ClosedStream, Maybe StdStream)

data UseProvidedHandle

Use the Handle provided by the CreateProcess value. This would allow you, for example, to open up a Handle to a file, set it as std_out, and avoid any additional overhead of dealing with providing that data to your process.

Since 0.1.4

Constructors

UseProvidedHandle

Instances

OutputSink UseProvidedHandle

Defined in Data.Streaming.Process

Methods

osStdStream :: (Maybe Handle -> IO UseProvidedHandle, Maybe StdStream)

InputSource UseProvidedHandle

Defined in Data.Streaming.Process

Methods

isStdStream :: (Maybe Handle -> IO UseProvidedHandle, Maybe StdStream)

Process handle

data StreamingProcessHandle

Wraps up the standard ProcessHandle to avoid the waitForProcess deadlock. See the linked documentation from the module header for more information.

Since 0.1.4

waitForStreamingProcess :: MonadIO m => StreamingProcessHandle -> m ExitCode

Blocking call to wait for a process to exit.

Since 0.1.4

waitForStreamingProcessSTM :: StreamingProcessHandle -> STM ExitCode

STM version of waitForStreamingProcess.

Since 0.1.4

getStreamingProcessExitCode :: MonadIO m => StreamingProcessHandle -> m (Maybe ExitCode)

Non-blocking call to check for a process exit code.

Since 0.1.4

getStreamingProcessExitCodeSTM :: StreamingProcessHandle -> STM (Maybe ExitCode)

STM version of getStreamingProcessExitCode.

Since 0.1.4

streamingProcessHandleRaw :: StreamingProcessHandle -> ProcessHandle

Get the raw ProcessHandle from a StreamingProcessHandle. Note that you should avoid using this to get the process exit code, and instead use the provided functions.

Since 0.1.4

streamingProcessHandleTMVar :: StreamingProcessHandle -> TMVar ExitCode

Get the TMVar storing the process exit code. In general, one of the above functions should be used instead to avoid accidentally corrupting the variable's state..

Since 0.1.4

Type classes

class InputSource a

Class for all things which can be used to provide standard input.

Since 0.1.4

Minimal complete definition

isStdStream

Instances

InputSource Handle

Defined in Data.Streaming.Process.Internal

Methods

isStdStream :: (Maybe Handle -> IO Handle, Maybe StdStream)

InputSource ClosedStream

Defined in Data.Streaming.Process

Methods

isStdStream :: (Maybe Handle -> IO ClosedStream, Maybe StdStream)

InputSource Inherited

Defined in Data.Streaming.Process

Methods

isStdStream :: (Maybe Handle -> IO Inherited, Maybe StdStream)

InputSource UseProvidedHandle

Defined in Data.Streaming.Process

Methods

isStdStream :: (Maybe Handle -> IO UseProvidedHandle, Maybe StdStream)

class OutputSink a

Class for all things which can be used to consume standard output or error.

Since 0.1.4

Minimal complete definition

osStdStream

Instances

OutputSink Handle

Defined in Data.Streaming.Process.Internal

Methods

osStdStream :: (Maybe Handle -> IO Handle, Maybe StdStream)

OutputSink ClosedStream

Defined in Data.Streaming.Process

Methods

osStdStream :: (Maybe Handle -> IO ClosedStream, Maybe StdStream)

OutputSink Inherited

Defined in Data.Streaming.Process

Methods

osStdStream :: (Maybe Handle -> IO Inherited, Maybe StdStream)

OutputSink UseProvidedHandle

Defined in Data.Streaming.Process

Methods

osStdStream :: (Maybe Handle -> IO UseProvidedHandle, Maybe StdStream)

Checked processes

withCheckedProcess :: (InputSource stdin, OutputSink stderr, OutputSink stdout, MonadIO m) => CreateProcess -> (stdin -> stdout -> stderr -> m b) -> m b

Run a process and supply its streams to the given callback function. After the callback completes, wait for the process to complete and check its exit code. If the exit code is not a success, throw a ProcessExitedUnsuccessfully.

NOTE: This function does not kill the child process or ensure resources are cleaned up in the event of an exception from the provided function. For that, please use withCheckedProcessCleanup from the conduit-extra package.

Since 0.1.7

data ProcessExitedUnsuccessfully

Indicates that a process exited with an non-success exit code.

Since 0.1.7

Constructors

ProcessExitedUnsuccessfully CreateProcess ExitCode

Instances

Show ProcessExitedUnsuccessfully

Defined in Data.Streaming.Process

Methods

showsPrec :: Int -> ProcessExitedUnsuccessfully -> ShowS

show :: ProcessExitedUnsuccessfully -> String

showList :: [ProcessExitedUnsuccessfully] -> ShowS

Exception ProcessExitedUnsuccessfully

Defined in Data.Streaming.Process

Methods

toException :: ProcessExitedUnsuccessfully -> SomeException

fromException :: SomeException -> Maybe ProcessExitedUnsuccessfully

displayException :: ProcessExitedUnsuccessfully -> String

Reexport

module System.Process