Haskell - ANSI > Escape Code > Select Graphic Rendition

Code Snippet

src/Data/ANSI/EscapeCode.hs

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{-# LANGUAGE Safe #-}

--------------------------------------------------------------------------------

module Data.ANSI.EscapeCode
  ( Colour
    ( Black
    , Red
    , Green
    , Yellow
    , Blue
    , Magenta
    , Cyan
    , White
    )
  , Frecuency
    ( Slow
    , Fast
    )
  --
  , sgr
  --
  , foreground
  , background
  , bold
  , faint
  , italic
  , underline
  , blink
  ) where

--------------------------------------------------------------------------------

data Colour
  = Black
  | Red
  | Green
  | Yellow
  | Blue
  | Magenta
  | Cyan
  | White
  deriving (Eq)

instance Enum Colour where
  fromEnum Black   = 0
  fromEnum Red     = 1
  fromEnum Green   = 2
  fromEnum Yellow  = 3
  fromEnum Blue    = 4
  fromEnum Magenta = 5
  fromEnum Cyan    = 6
  fromEnum White   = 7

  toEnum 0 = Black
  toEnum 1 = Red
  toEnum 2 = Green
  toEnum 3 = Yellow
  toEnum 4 = Blue
  toEnum 5 = Magenta
  toEnum 6 = Cyan
  toEnum 7 = White
  toEnum _ = error "Colour code not supported"

  succ Black   = Red
  succ Red     = Green
  succ Green   = Yellow
  succ Yellow  = Blue
  succ Blue    = Magenta
  succ Magenta = Cyan
  succ Cyan    = White
  succ White   = Black

  pred Black   = White
  pred Red     = Black
  pred Green   = Red
  pred Yellow  = Green
  pred Blue    = Yellow
  pred Magenta = Blue
  pred Cyan    = Magenta
  pred White   = Cyan


type Bright = Bool

data Background = BG !Bool Bright Colour
data Foreground = FG !Bool Bright Colour

data Frecuency
  = Slow
  | Fast

data Blink = B !Bool Frecuency

data SelectGraphicRendition
  = SGR !Background !Foreground !Bool !Bool !Bool !Bool !Blink String

instance Show SelectGraphicRendition where
  show (SGR bg fg bo fa it un bl text) =
    "\ESC[" ++
    "0"     ++
    (cb bg) ++
    (cf fg) ++
    (fb bo) ++
    (ff fa) ++
    (fi it) ++
    (fu un) ++
    (bf bl) ++
    "m"     ++
    text    ++
    "\ESC[00m"
    where
      cb (BG True  True  c) = ";" ++ (show $ 60 + 40 + fromEnum c)
      cb (BG True  False c) = ";" ++ (show $      40 + fromEnum c)
      cb (BG False _____ _) = [                                  ]
      cf (FG True  True  c) = ";" ++ (show $ 60 + 30 + fromEnum c)
      cf (FG True  False c) = ";" ++ (show $      30 + fromEnum c)
      cf (FG False _____ _) = [                                  ]
      fb     True  = ";01"
      fb     False = [   ]
      ff     True  = ";02"
      ff     False = [   ]
      fi     True  = ";03"
      fi     False = [   ]
      fu     True  = ";04"
      fu     False = [   ]
      bf (B  True  Slow) = ";05"
      bf (B  True  Fast) = ";06"
      bf (B  False ____) = [   ]

--------------------------------------------------------------------------------

sgr
  :: String
  -> SelectGraphicRendition

foreground
  :: Bright
  -> Colour
  -> SelectGraphicRendition
  -> SelectGraphicRendition

background
  :: Bright
  -> Colour
  -> SelectGraphicRendition
  -> SelectGraphicRendition

bold
  :: SelectGraphicRendition
  -> SelectGraphicRendition

faint
  :: SelectGraphicRendition
  -> SelectGraphicRendition

italic
  :: SelectGraphicRendition
  -> SelectGraphicRendition

underline
  :: SelectGraphicRendition
  -> SelectGraphicRendition

blink
  :: Frecuency
  -> SelectGraphicRendition
  -> SelectGraphicRendition

--------------------------------------------------------------------------------
sgr =
  SGR bg fg bo fa it un bl
  where
    fg = FG False undefined undefined
    bg = BG False undefined undefined
    bo = False
    fa = False
    it = False
    un = False
    bl = B False undefined

--------------------------------------------------------------------------------

foreground b c (SGR bg __ bo fa it un bl txt) =
  SGR bg fg bo fa it un bl txt
  where
    fg = FG True b c

background b c (SGR __ fg bo fa it un bl txt) =
  SGR bg fg bo fa it un bl txt
  where
    bg = BG True b c

bold (SGR bg fg __ fa it un bl txt) =
  SGR bg fg bo fa it un bl txt
  where
    bo = True

faint (SGR bg fg bo __ it un bl txt) =
  SGR bg fg bo fa it un bl txt
  where
    fa = True

italic (SGR bg fg bo fa __ un bl txt) =
  SGR bg fg bo fa it un bl txt
  where
    it = True

underline (SGR bg fg bo fa it __ bl txt) =
  SGR bg fg bo fa it un bl txt
  where
    un = True

blink f (SGR bg fg bo fa it un __ txt) =
  SGR bg fg bo fa it un bl txt
  where
    bl = B True f

--------------------------------------------------------------------------------

-- References
--
-- ANSI escape code:
-- * https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_parameters

src/Main.hs

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#!/usr/bin/env stack
{- stack
   --resolver lts-13.30
   --install-ghc
   script
   --ghc-options -Werror
   --ghc-options -Wall
   --
-}

--------------------------------------------------------------------------------

module Main (main) where

--------------------------------------------------------------------------------

import           Data.Word
  ( Word8
  )

import           Data.ANSI.EscapeCode
  ( Colour (Black, Blue, Green, Red, Yellow)
  , Frecuency (Fast)
  , background
  , blink
  , bold
  , faint
  , foreground
  , italic
  , sgr
  , underline
  )

--------------------------------------------------------------------------------

codes :: [String]
codes =
  map f [ 0 .. 107 ]
  where
    f :: Word8 -> String
    f n = "\ESC[" ++ show n ++ "m " ++ g n ++ "\ESC[m"
    g n = leftpad 3 (Just ' ') $ show n

main :: IO ()
main =
  (putStrLn "# As in the `Example of use in C`:") >>
  (mapM_ (putStrLn . concat) $ chunksOf 10 $ codes) >>
  (putStrLn "") >>
  (putStrLn "# Using the Data.ANSI.EscapeCode module:") >>
  (putStrLn . show . f $ t) >>
  (putStrLn . show . g $ t) >>
  (putStrLn . show . h $ t)
  where
    f = bold . blink Fast . foreground True Yellow . background False Red . sgr
    g = underline . foreground False Black . background True Green . sgr
    h = faint . italic . foreground False Black . background True Blue . sgr
    t = "this is just some text"

--------------------------------------------------------------------------------

-- HELPERS

leftpad :: Int -> Maybe Char -> String -> String
leftpad n m x =
  if l > n
  then x
  else replicate (n-l) c ++ x
  where
    l = length x
    c =
      case m of
        Just  v ->  v
        Nothing -> '.'

chunksOf :: Int -> [a] -> [[a]]
chunksOf _ [] = [               ]
chunksOf n bs = x : chunksOf n xs
  where
    (x,xs) = splitAt n bs

--------------------------------------------------------------------------------

-- References
--
-- ANSI escape code:
-- * https://en.wikipedia.org/wiki/ANSI_escape_code#Example_of_use_in_C

src/package.cabal

cabal-version: 1.12

name:           package
version:        0.11.0.0
build-type:     Simple

executable ansi-color
  main-is:
      Main.hs
  other-modules:
      Paths_package
      Data.ANSI.EscapeCode
  hs-source-dirs:
      ./.
  ghc-options:
      ---------------------------------------------------------------------------
      -- GHC 8.6.4 Users Guide > 9. Using GHC > 9.2. Warnings and sanity-checking
      -- * Base: https://downloads.haskell.org/~ghc/8.6.4/docs/html/users_guide/
      -- * File: using-warnings.html
      -- Warnings that are not enabled by -Wall:
      ---------------------------------------------------------------------------
      -Wall
      -Wincomplete-record-updates
      -- -Wmonomorphism-restriction
      -- -Wimplicit-prelude
      -- -Wmissing-local-signatures
      -Wmissing-exported-signatures
      -- -Wmissing-export-lists
      -- -Wmissing-import-lists
      -Wmissing-home-modules
      -Widentities
      -Wredundant-constraints
      -- Added since GHC 8.4
      -Wpartial-fields 
      -- -Wmissed-specialisations
      -- -Wall-missed-specialisations
      ---------------------------------------------------------------------------
      -- Added to allow instance definition in other files, in order to keep the 
      -- Effect module SAFE so it can be imported by the Process
      ---------------------------------------------------------------------------
      -Wno-orphans
      -- Makes any warning into a fatal error.
      -Werror
      ---------------------------------------------------------------------------
      -- Deterministic builds (Uniques):
      -- * https://gitlab.haskell.org/ghc/ghc/wikis/deterministic-builds#progress
      -- * https://www.youtube.com/watch?v=FNzTk4P4fL4 (08 GHC Determinism ICFP)
      ---------------------------------------------------------------------------
      -dinitial-unique=0
      -dunique-increment=1
      ---------------------------------------------------------------------------
      -- The -N flag built-in can be modified on runtime based on the system
      -- hosting the binary for optimal performance:
      -- - https://hackage.haskell.org/package/base/docs/GHC-Conc.html
      --   * getNumProcessors
      -- - https://hackage.haskell.org/package/base/docs/Control-Concurrent.html
      --   * setNumCapabilities
      ---------------------------------------------------------------------------
      -- 12.40. Safe Haskell > ... > 12.40.1.1. Strict type-safety (good style)
      -- * Enforce good style, similar to the function of -Wall.
      -XSafe
      -fpackage-trust
      -trust=base
      -- Only Trustworthy packages can be trusted
      -- * Base: https://downloads.haskell.org/~ghc/8.6.4/docs/html/users_guide/
      -- * File: safe_haskell.html
      ---------------------------------------------------------------------------
      -O2
      -threaded
      -rtsopts
      -with-rtsopts=-N
  build-depends:
      -- Prelude
      base
  default-language:
      Haskell98

stack.yaml

resolver: lts-13.30
packages:
  - src
nix:
  enable: true
  packages: []
  path: [
    "nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/6420e26.tar.gz"
  ]
  
## Reference
# Stack:
# - https://www.stackage.org/lts-13.30
# NixOS:
# - https://github.com/NixOS/nixpkgs-channels/branches/active
# - https://github.com/NixOS/nixpkgs-channels/tree/nixos-19.03
# - https://github.com/NixOS/nixpkgs-channels/tree/6420e26
# - https://github.com/NixOS/nixpkgs-channels/archive/6420e26.tar.gz

build.bash

#!/usr/bin/env bash

clear

src="$(stack path --local-install-root)/bin"
tgt="./bin"

echo "### Clearing binary files:"
find $tgt -mindepth 1 -name "*" -delete -print
echo

echo "### Stack cleaning and building:" 
stack build
echo

echo "### Copying binary to local $tgt:" 
if [ ! -d $tgt ]; then
  mkdir -p $tgt;
fi
cp -v $src/* $tgt/
echo

bin=$(ls $tgt) # We need to ls after binaries are created
echo "### Repoducible hashes:"
for f in $bin; do
    echo -e $(sha256sum $tgt/$f | cut -d " " -f 1): $f
done;
echo

Code Output:

./build.bash && ./bin/ansi-color
### Clearing binary files:
./bin/ansi-color

### Stack cleaning and building:

### Copying binary to local ./bin:
'/home/johndoe/code/haskell/ansi-color/.stack-work/install/x86_64-linux-nix/e07ba7d58ca3cbf46d17cb550fd0dc7ccd1bfc735df47120e593b662560d5c08/8.6.5/bin/ansi-color' -> './bin/ansi-color'

### Repoducible hashes:
75843be327c60bb8f6c210111320a6370eb0997261a46d904d32db7f3b490bc7: ansi-color

ANSI > Escape Code > Select Graphic Rendition (blinking)

References:

Wikipedia (ANSI escape code):
- [Select Graphic Rendition (SGR) parameters][dag]
- Example of use in C

Blog: Mr. Mathiesen

Haskell - ANSI > Escape Code > Select Graphic Rendition

Code Snippet

src/Data/ANSI/EscapeCode.hs

src/Main.hs

src/package.cabal

stack.yaml

build.bash

Code Output:

References: