Data.Streaming.Process

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

Safe Haskell | Safe
Language | Haskell98

Data.Streaming.Process

Contents

- Functions
- Specialized streaming types
- Process handle
- Type classes
- Checked processes
- Reexport

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

- streamingProcess :: (MonadIO m, InputSource stdin, OutputSink stdout, OutputSink stderr) => CreateProcess -> m (stdin, stdout, stderr, StreamingProcessHandle)
- data Inherited = Inherited
- data ClosedStream = ClosedStream
- data UseProvidedHandle = UseProvidedHandle
- data StreamingProcessHandle
- waitForStreamingProcess :: MonadIO m => StreamingProcessHandle -> m ExitCode
- waitForStreamingProcessSTM :: StreamingProcessHandle -> STM ExitCode
- getStreamingProcessExitCode :: MonadIO m => StreamingProcessHandle -> m (Maybe ExitCode)
- getStreamingProcessExitCodeSTM :: StreamingProcessHandle -> STM (Maybe ExitCode)
- streamingProcessHandleRaw :: StreamingProcessHandle -> ProcessHandle
- streamingProcessHandleTMVar :: StreamingProcessHandle -> TMVar ExitCode
- class InputSource a
- class OutputSink a
- withCheckedProcess :: (InputSource stdin, OutputSink stderr, OutputSink stdout, MonadIO m) => CreateProcess -> (stdin -> stdout -> stderr -> m b) -> m b
- data ProcessExitedUnsuccessfully = ProcessExitedUnsuccessfully CreateProcess ExitCode
- module System.Process

# 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

OutputSink Inherited |
InputSource Inherited |

data ClosedStream

Close the stream with the child process.

Since 0.1.4

Constructors

ClosedStream |

Instances

OutputSink ClosedStream |
InputSource ClosedStream |

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 |
InputSource UseProvidedHandle |

# 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 |
InputSource ClosedStream |
InputSource Inherited |
InputSource UseProvidedHandle |

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 |
OutputSink ClosedStream |
OutputSink Inherited |
OutputSink UseProvidedHandle |

# 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

Show ProcessExitedUnsuccessfully |
Exception ProcessExitedUnsuccessfully |

# Reexport

module System.Process