System.Console.Regions

concurrent-output-1.10.21: Ungarble output from several threads or commands

Copyright | 2015 Joey Hess <id@joeyh.name>
License | BSD-2-clause
Safe Haskell | None
Language | Haskell2010

System.Console.Regions

Contents

- Types
- Initialization
- Region content and display
- STM region contents

Description

Console regions are displayed near the bottom of the console, and can be updated concurrently by threads.

Any other output lines displayed using `outputConcurrent` and `createProcessConcurrent` will scroll up above the open console regions.

For example, this program:

     import Control.Concurrent.Async
     import Control.Concurrent
     import System.Console.Concurrent
     import System.Console.Regions
     import System.Process

     main = displayConsoleRegions $ do
     	mapConcurrently download [1..5]
    		`concurrently` mapM_ message [1..10]
    		`concurrently` createProcessConcurrent (proc "echo" ["hello world"])

     message :: Int -> IO ()
     message n = do
     	threadDelay 500000
     	outputConcurrent ("Message " ++ show n ++ "\n")

     download :: Int -> IO ()
     download n = withConsoleRegion Linear $ \r -> do
     	setConsoleRegion r basemsg
     	go n r
       where
     	basemsg = "Download " ++ show n
    	go c r
    		| c < 1 = finishConsoleRegion r (basemsg ++ " done!")
     		| otherwise = do
     			threadDelay 1000000
     			appendConsoleRegion r " ... "
     			go (c-1) r

Will display like this:

    Message 1
    hello world
    Message 2
    Download 1 ...
    Download 2 ...
    Download 3 ...

Once the 1st download has finished, and another message has displayed, the console will update like this:

    Message 1
    hello world
    Message 2
    Download 1 done!
    Message 3
    Download 2 ... ...
    Download 3 ... ...

Synopsis

- data ConsoleRegion
- data RegionLayout
  - = Linear
  - | InLine ConsoleRegion
- class ToRegionContent v where
  - toRegionContent :: v -> RegionContent
- newtype RegionContent = RegionContent (STM Text)
- class LiftRegion (m :: Type -> Type) where
  - liftRegion :: STM a -> m a
- displayConsoleRegions :: (MonadIO m, MonadMask m) => m a -> m a
- withConsoleRegion :: (MonadIO m, MonadMask m) => RegionLayout -> (ConsoleRegion -> m a) -> m a
- openConsoleRegion :: LiftRegion m => RegionLayout -> m ConsoleRegion
- newConsoleRegion :: (LiftRegion m, ToRegionContent v) => RegionLayout -> v -> m ConsoleRegion
- closeConsoleRegion :: LiftRegion m => ConsoleRegion -> m ()
- setConsoleRegion :: (ToRegionContent v, LiftRegion m) => ConsoleRegion -> v -> m ()
- appendConsoleRegion :: (Outputable v, LiftRegion m) => ConsoleRegion -> v -> m ()
- finishConsoleRegion :: (Outputable v, LiftRegion m) => ConsoleRegion -> v -> m ()
- getConsoleRegion :: LiftRegion m => ConsoleRegion -> m Text
- tuneDisplay :: LiftRegion m => ConsoleRegion -> (Text -> STM Text) -> m ()
- consoleWidth :: STM Int
- consoleHeight :: STM Int
- regionList :: TMVar [ConsoleRegion]
- waitDisplayChange :: STM a -> IO a

# Types

data ConsoleRegion #

A handle allowing access to a region of the console.

#### Instances

Instances details

Eq ConsoleRegion # |
Instance details Defined in System.Console.Regions Methods (==) :: ConsoleRegion -> ConsoleRegion -> Bool # (/=) :: ConsoleRegion -> ConsoleRegion -> Bool #

data RegionLayout #

Controls how a region is laid out in the console.

Here's an annotated example of how the console layout works. Each sequence of the same letter represents a distinct region.

    scrolling......
    scrolling......
    scrolling......
    aaaaaa......... -- Linear
    bbbbbbbbbbbbbbb -- Linear
    bbb............       (expanded to multiple lines)
    ccccccccc...... -- Linear
    ddddeeeefffffff -- [InLine]
    fffffggggg.....       (expanded to multiple lines)

Constructors

Linear |
InLine ConsoleRegion |

#### Instances

Instances details

Eq RegionLayout # |
Instance details Defined in System.Console.Regions Methods (==) :: RegionLayout -> RegionLayout -> Bool # (/=) :: RegionLayout -> RegionLayout -> Bool #

class ToRegionContent v where #

Values that can be displayed in a region.

Methods

toRegionContent :: v -> RegionContent #

#### Instances

Instances details

ToRegionContent Text # |
Instance details Defined in System.Console.Regions Methods toRegionContent :: Text -> RegionContent #
ToRegionContent Text # | Note that using a lazy Text in a region will buffer it all in memory.
Instance details Defined in System.Console.Regions Methods toRegionContent :: Text -> RegionContent #
ToRegionContent String # |
Instance details Defined in System.Console.Regions Methods toRegionContent :: String -> RegionContent #
ToRegionContent (STM Text) # | Makes a STM action be run to get the content of a region. Any change to the values that action reads will result in an immediate refresh of the display.
Instance details Defined in System.Console.Regions Methods toRegionContent :: STM Text -> RegionContent #

newtype RegionContent #

Constructors

RegionContent (STM Text) |

class LiftRegion (m :: Type -> Type) where #

Many actions in this module can be run in either the IO monad or the STM monad. Using STM allows making several changes to the displayed regions atomically, with the display updated a single time.

Methods

liftRegion :: STM a -> m a #

#### Instances

Instances details

LiftRegion STM # |
Instance details Defined in System.Console.Regions Methods liftRegion :: STM a -> STM a #
LiftRegion IO # |
Instance details Defined in System.Console.Regions Methods liftRegion :: STM a -> IO a #

# Initialization

displayConsoleRegions :: (MonadIO m, MonadMask m) => m a -> m a #

Handles all display for the other functions in this module.

Note that this uses `lockOutput`, so it takes over all output to the console while the passed IO action is running. As well as displaying the console regions, this handles display of anything buffered by `outputConcurrent` and `createProcessConcurrent`. So, `withConcurrentOutput` and `flushConcurrentOutput` should not be run while this is in use, and will block.

When standard output is not an ANSI capable terminal, console regions are not displayed.

withConsoleRegion :: (MonadIO m, MonadMask m) => RegionLayout -> (ConsoleRegion -> m a) -> m a #

Runs the action with a new console region, closing the region when the action finishes or on exception.

openConsoleRegion :: LiftRegion m => RegionLayout -> m ConsoleRegion #

Opens a new console region.

newConsoleRegion :: (LiftRegion m, ToRegionContent v) => RegionLayout -> v -> m ConsoleRegion #

Makes a new region, but does not add it to the display.

closeConsoleRegion :: LiftRegion m => ConsoleRegion -> m () #

Closes a console region. Once closed, the region is removed from the display.

# Region content and display

setConsoleRegion :: (ToRegionContent v, LiftRegion m) => ConsoleRegion -> v -> m () #

Sets the value of a console region. This will cause the console to be updated to display the new value.

It's fine for the value to be longer than the terminal is wide, or to include newlines ('n'). Regions expand to multiple lines as necessary.

The value can include ANSI SGR escape sequences for changing the colors of all or part of a region. For this to display properly, a reset escape sequence must be included to get the color back to default. System.Console.ANSI makes it easy to construct such values. For example:

     import System.Console.ANSI

     setConsoleRegion region
     	( "hello "
     	<> setSGRCode [SetColor Foreground Vivid Red]
    	<> "Mars"
    	<> setSGRCode [Reset]
     	<> "!"
    	)

Other ANSI escape sequences, especially those doing cursor movement, will mess up the layouts of regions. Caveat emptor.

ANSI SGR escape sequences that span multiple lines do not currently display as you might hope. (Patches would be accepted.)

appendConsoleRegion :: (Outputable v, LiftRegion m) => ConsoleRegion -> v -> m () #

Appends a value to the current value of a console region.

    appendConsoleRegion progress "." -- add another dot to progress display

finishConsoleRegion :: (Outputable v, LiftRegion m) => ConsoleRegion -> v -> m () #

Closes the console region, and displays the passed value in the scrolling area above the active console regions. When Nothing is passed, displays the current value of the console region.

getConsoleRegion :: LiftRegion m => ConsoleRegion -> m Text #

Gets the current content of a console region.

tuneDisplay :: LiftRegion m => ConsoleRegion -> (Text -> STM Text) -> m () #

Changes how a console region displays.

Each time the region's value changes, the STM action is provided with the current value of the region, and returns the value to display.

For example, this will prevent a region from ever displaying more than 10 characters wide, and will make it display text reversed:

    tuneDisplay myregion $ pure . T.take 10
    tuneDisplay myregion $ pure . T.reverse

Note that repeated calls to tuneDisplay are cumulative.

Normally, the STM action should avoid retrying, as that would block all display updates.

# STM region contents

The `ToRegionContent` instance for `STM` `Text` can be used to make regions that automatically update whenever there's a change to any of the STM values that they use.

For example, a region that displays the screen size, and automatically refreshes it:

    import qualified Data.Text as T

     r <- openConsoleRegion Linear s
     setConsoleRegion r $ do
     	w <- readTVar consoleWidth
     	h <- readTVar consoleHeight
     	return $ T.pack $ unwords
     		[ "size:"
    		, show w
     		, "x"
    		, show h
     		]

consoleWidth :: STM Int #

Gets the width of the console.

On Unix, this is automatically updated when the terminal is resized. On Windows, it is determined at start. On WASM, the console width is hard coded to 80 since WASI does not provide a way to determine it.

consoleHeight :: STM Int #

Get the height of the console.

On Unix, this is automatically updated when the terminal is resized. On Windows, it is determined at start. On WASM, the console heigth is hard coded to 25 since WASI does not provide a way to determine it.

regionList :: TMVar [ConsoleRegion] #

All the regions that are currently displayed on the screen.

The list is ordered from the bottom of the screen up. Reordering it will change the order in which regions are displayed. It's also fine to remove, duplicate, or add new regions to the list.

waitDisplayChange :: STM a -> IO a #

Runs a STM action, and waits for the display to be fully updated with any changes that action makes to the displayed regions.