streaming-commons-0.1.15.5: Common lower-level functions needed by various streaming data libraries

Safe HaskellSafe
LanguageHaskell98

Data.Streaming.Process

Contents

Description

A full tutorial for this module is available on FP School of Haskell: https://www.fpcomplete.com/user/snoyberg/library-documentation/data-conduit-process.

Note that, while the tutorial covers Data.Streaming.Process, this module is the basis of the streaming version, and almost all concepts there apply here.

Synopsis

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

Specialized streaming types

data Inherited

Inherit the stream from the current process.

Since 0.1.4

Constructors

Inherited 

Instances

data ClosedStream

Close the stream with the child process.

Since 0.1.4

Constructors

ClosedStream 

Instances

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

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

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

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 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

Reexport

module System.Process