System.Process.Microlens.StdStream

This module provides the associated optics and combinators for working with StdStream objects. StdStream consists of four cases, for which we provide traversals for each case

Traversals

_Inherit :: Traversal' StdStream StdStream

A Traversal' into the Inherit structure of a StdStream

_UseHandle :: Traversal' StdStream Handle

A Traversal' into the UseHandle structure's Handle for a StdStream

_CreatePipe :: Traversal' StdStream StdStream

A Traversal' into the CreatePipe structure of a StdStream

_NoStream :: Traversal' StdStream StdStream

A Traversal' into the NoStream structure of a StdStream

Classy Traversals

class IsCreatePipe a where

Class constraint proving a type has a prism into a Handle via a UseHandle structure. Any StdStream will have a prism into CreatePipe - it is just an overwrite to CreatePipe

Methods

_CreatesPipe :: Traversal' a StdStream

Instances

IsCreatePipe StdStream

Defined in System.Process.Microlens.StdStream

Methods

_CreatesPipe :: Traversal' StdStream StdStream

class IsInherit a where

Class constraint proving a type has a prism into an Inherit structure. Any StdStream will have a prism into Inherit - it is just an overwrite to Inherit

Methods

_Inherits :: Traversal' a StdStream

Instances

IsInherit StdStream

Defined in System.Process.Microlens.StdStream

Methods

_Inherits :: Traversal' StdStream StdStream

class IsUseHandle a where

Class constraint proving a type has a prism into a Handle via a UseHandle structure.

Methods

_UsesHandle :: Traversal' a Handle

Instances

IsUseHandle StdStream

Defined in System.Process.Microlens.StdStream

Methods

_UsesHandle :: Traversal' StdStream Handle

class IsNoStream a where

Class constraint proving a type has a prism into a Handle via a UseHandle structure. Any StdStream will have a prism into NoStream - it is just an overwrite to NoStream.

Methods

_NoStreams :: Traversal' a StdStream

Instances

IsNoStream StdStream

Defined in System.Process.Microlens.StdStream

Methods

_NoStreams :: Traversal' StdStream StdStream

Combinators

inheriting :: Lens' a StdStream -> a -> a

Given a lens into a StdStream, overwrite to Inherit so that the stream inherits from its parent process

Examples:

>>> inheriting ($) CreatePipe
Inherit

piping :: Lens' a StdStream -> a -> a

Given a lens into a StdStream, overwrite to CreatePipe.

Examples:

>>> piping ($) NoStream
CreatePipe

handling :: Lens' a StdStream -> Handle -> a -> a

Given a lens into a StdStream and a handle, set the handle using UseHandle. Note that this is the only really interesting case for anything with a lens into a handle inculding StdStream.

Examples:

>>> handling ($) System.stdin $ UseHandle System.stdout
UseHandle {handle: <stdin>}

>>> handling ($) System.stdout Inherit
UseHandle {handle: <stdout>}

nostreaming :: Lens' a StdStream -> a -> a

Given a lens into a StdStream, set to NoStream

Examples:

>>> nostreaming ($) Inherit
NoStream