streaming-commons-0.1.17: Common lower-level functions needed by various streaming data libraries

Safe HaskellSafe




A full tutorial for this module is available at:

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.



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



data ClosedStream #

Close the stream with the child process.

Since 0.1.4



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



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


class OutputSink a #

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

Since 0.1.4

Minimal complete definition


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