System.Process.Lens.StdStream

This module provides the associated optics and combinators for working with StdStream objects. StdStream consists of four cases, for which we provide prisms and classy variants, as well as a single Review for the only non-trivial Review - UseHandle.

Prisms

_Inherit :: Prism' StdStream StdStream

A prism into the Inherit structure of a StdStream

Examples:

>>> _Inherit # CreatePipe
Inherit

_UseHandle :: Prism' StdStream Handle

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

Examples:

>>> _UseHandle # System.stdin
UseHandle {handle: <stdin>}

_CreatePipe :: Prism' StdStream StdStream

A prism into the CreatePipe structure of a StdStream

Examples:

>>> _CreatePipe # Inherit
CreatePipe

_NoStream :: Prism' StdStream StdStream

A prism into the NoStream structure of a StdStream

Examples:

>>> _NoStream # CreatePipe
NoStream

Classy Prisms

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 :: Prism' a StdStream

Instances

IsInherit StdStream

Defined in System.Process.Lens.StdStream

Methods

_Inherits :: Prism' StdStream StdStream

class IsUseHandle a where

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

Methods

_UsesHandle :: Prism' a Handle

Instances

IsUseHandle StdStream

Defined in System.Process.Lens.StdStream

Methods

_UsesHandle :: Prism' StdStream Handle

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 :: Prism' a StdStream

Instances

IsCreatePipe StdStream

Defined in System.Process.Lens.StdStream

Methods

_CreatesPipe :: Prism' StdStream StdStream

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 :: Prism' a StdStream

Instances

IsNoStream StdStream

Defined in System.Process.Lens.StdStream

Methods

_NoStreams :: Prism' StdStream StdStream

Combinators

usehandleOf :: IsUseHandle a => Handle -> a

Inject a handle into something with a prism into the handle

Examples:

>>> usehandleOf @StdStream System.stdin
UseHandle {handle: <stdin>}

inheriting :: IsInherit a => 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 :: IsCreatePipe a => Lens' a StdStream -> a -> a

Given a lens into a StdStream, overwrite to CreatePipe.

Examples:

>>> piping ($) NoStream
CreatePipe

handling :: IsUseHandle a => 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.stdin NoStream
NoStream

>>> handling ($) System.stdin Inherit
Inherit

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

Given a lens into a StdStream, set to NoStream

Examples:

>>> nostreaming ($) Inherit
NoStream