System.Console.Style

This library provides styled text output using ANSI escape sequences. The main feature is that the library keeps track of a stack of the active styles using a state monad. This makes it easy to use this library for a pretty printer with nested annotations, e.g., wl-pprint-console.

Warning: Windows support is currently not implemented, but is planned (by using ansi-terminal or the ffi).

Example:

basicExample :: IO ()
basicExample = runWithStyle [FgColor Blue] $ do
  withStyle [Bold] $ liftIO $ putStr "Bold Blue"

  setStyle [Save, Italic, BgColor Red]
  liftIO $ putStr "Italic Red"
  setStyle [Restore]

  setStyle [Under]
  liftIO $ putStr "Under Blue"
  setStyle [Reset]

  liftIO $ putStrLn "Normal output"

For many more examples, see the Example.hs file.

Documentation

data Color

Console color

Constructors

DefaultColor

Default terminal color (terminal specific)

Black

Red

Green

Yellow

Blue

Magenta

Cyan

White

DullBlack

DullRed

DullGreen

DullYellow

DullBlue

DullMagenta

DullCyan

DullWhite

Color256 !Word8

Color from 256 color scheme. Color is automatically reduced to 8 colors for less capable terminals.

RGB !Word8 !Word8 !Word8

True color. Color is automatically reduced to 256 or 8 colors for less capable terminals.

Instances

Eq Color

Methods

(==) :: Color -> Color -> Bool

(/=) :: Color -> Color -> Bool

Ord Color

Methods

compare :: Color -> Color -> Ordering

(<) :: Color -> Color -> Bool

(<=) :: Color -> Color -> Bool

(>) :: Color -> Color -> Bool

(>=) :: Color -> Color -> Bool

max :: Color -> Color -> Color

min :: Color -> Color -> Color

Show Color

Methods

showsPrec :: Int -> Color -> ShowS

show :: Color -> String

showList :: [Color] -> ShowS

class HasStyle s where

State accessor for the Style

Minimal complete definition

getStyle, putStyle

Methods

getStyle :: s -> Style

putStyle :: Style -> s -> s

Instances

HasStyle Style

Methods

getStyle :: Style -> Style

putStyle :: Style -> Style -> Style

data SetStyle

Style commands

Constructors

Bold

Bold font

NotBold

Normal-weight font

Italic

Italic font

NotItalic

Non-italic font

Under

Underlined text

NotUnder

Text without underline

Invert

Invert foreground and background color

NotInvert

Deactivate color inversion

Save

Save style to stack

Restore

Restore style from stack

Reset

Reset to default style

Blink

Activate blinking

NotBlink

Deactivate blinking

FgColor !Color

BgColor !Color

Instances

Eq SetStyle

Methods

(==) :: SetStyle -> SetStyle -> Bool

(/=) :: SetStyle -> SetStyle -> Bool

Ord SetStyle

Methods

compare :: SetStyle -> SetStyle -> Ordering

(<) :: SetStyle -> SetStyle -> Bool

(<=) :: SetStyle -> SetStyle -> Bool

(>) :: SetStyle -> SetStyle -> Bool

(>=) :: SetStyle -> SetStyle -> Bool

max :: SetStyle -> SetStyle -> SetStyle

min :: SetStyle -> SetStyle -> SetStyle

Show SetStyle

Methods

showsPrec :: Int -> SetStyle -> ShowS

show :: SetStyle -> String

showList :: [SetStyle] -> ShowS

data Style

Abstract state datatype which keeps a stack of the applied styles.

Instances

HasStyle Style

Methods

getStyle :: Style -> Style

putStyle :: Style -> Style -> Style

data Term

Terminal type. For less capable terminals the color depth is automatically reduced.

Constructors

TermDumb

Dumb terminal - no color output

Term8

8 colors supported

Term256

256 colors supported

TermRGB

True colors supported

TermWin

Windows terminal. Will use emulation (Not yet implemented).

Instances

Eq Term

Methods

(==) :: Term -> Term -> Bool

(/=) :: Term -> Term -> Bool

Show Term

Methods

showsPrec :: Int -> Term -> ShowS

show :: Term -> String

showList :: [Term] -> ShowS

defaultStyle :: Term -> Style

The function (defaultStyle term) returns the default Style configured with terminal type term.

hDefaultStyle :: Handle -> Term -> Style

(hDefaultStyle handle term) return the default (initial) Style configured with the file handle handle and terminal type term@.

Every Style has a single associated handle.

hGetTerm :: MonadIO m => Handle -> m Term

The action (hGetTerm handle) determines the terminal type of the file handle.

The terminal type is determined by checking if the file handle points to a device and by looking at the $TERM environment variable.

hRunStyle :: MonadIO m => Handle -> StateT Style m a -> m a

The action (hRunStyle handle action) runs the StateT monad transformer providing the active Style for the given action.

hRunWithStyle :: (MonadIO m, Foldable f) => Handle -> f SetStyle -> StateT Style m a -> m a

The action (hRunWithStyle handle cmd action) runs the StateT monad transformer providing the active Style for the given action.

The output on handle within the action is modified by the given StyleSet commands cmd. The Style is restored to the defaults afterwards.

runStyle :: Term -> State Style a -> a

The action (runStyle term action) runs the State monad providing the active Style for the given action.

runStyleT :: Monad m => Term -> StateT Style m a -> m a

The action (runStyleT term action) runs the StateT monad transformer providing the active Style for the given action.

runWithStyle :: (MonadIO m, Foldable f) => f SetStyle -> StateT Style m a -> m a

The action (runWithStyle cmd action) runs the StateT monad transformer providing the active Style for the given action.

The output on stdout within the action is modified by the given StyleSet commands cmd. The Style is restored to the defaults afterwards.

setStyle :: (MonadIO m, MonadState s m, HasStyle s, Foldable f) => f SetStyle -> m ()

The action (setStyle cmd) modifies the active Style by executing the StyleSet commands cmd.

The style changes are applied immediately.

setStyleCode :: (MonadState s m, HasStyle s, Foldable f) => f SetStyle -> m String

The action (styleCode cmd) returns the ANSI code corresponding to the StyleSet commands cmd.

withStyle :: (MonadIO m, MonadState s m, HasStyle s, Foldable f) => f SetStyle -> m a -> m a

The action (withStyle cmd action) executes the action with the active Style modified by the StyleSet commands cmd.

The style is restored to the previous Style afterwards.

changeStyle :: (MonadState s m, HasStyle s, Foldable f) => f SetStyle -> m ()

The action (changeStyle cmd) modifies the active Style by executing the StyleSet commands cmd without applying the changes.

You have to call applyStyle or applyStyleCode afterwards!

applyStyle :: (MonadIO m, MonadState s m, HasStyle s) => m ()

The action applyStyle applies the latest style changes.

applyStyleCode :: (MonadState s m, HasStyle s) => m String

The action applyStyleCode returns the ANSI code for the latest style changes.