Produce Text with terminal escape sequences.
See README.md
escaped
Produce Text with terminal escape sequences.
Usage
Quick Start
{-# LANGUAGE OverloadedStrings #-}
module Main where
import Data.Semigroup ((<>))
import Data.Text.Escaped
import qualified Data.Text.IO as T
main :: IO ()
main = T.putStrLn $ render $ "This is " <> red "red" <> " text."
Example
Running the example executable will produce everything this library currently supports:
Helper Functions
The above uses the red helper function, which prefixes the given value with the (foreground) color red, then resets after.
NOTE: this function composes Escapeds, so you can nest:
"This is " <> red (bg Blue "red on blue") <> " text."
The Escaped Type
Behind those helpers, a Semigroup instance, and the OverLoadedStrings extension, what you're actually doing is building up a value of type Escaped:
λ> :set -XOverloadedStrings
λ> "one" <> red "red" <> "three"
Many [Plain "one",FG Red,Plain "red",Reset,Plain "three"]
λ> render it
"one\ESC[31mred\ESC[0mthree"
The Escaped type has constructors for the various shell escapes and is meant to be used directly for non-trivial cases.
"This is " <> Blink <> FG Red <> "blinking red" <> Reset <> " text."
If you need to interpolate non-literals of type Text, use the Plain constructor:
logMessage :: Level -> Text -> Escaped
logMessage l msg = "[" <> prefix <> "] " <> Plain msg
where
prefix :: Level -> Escaped
prefix Info = blue "INFO"
prefix Warn = yellow "WARN"
-- etc.
Terminal Applications
The terminalRenderer function queries if stdout is connected to a tty and returns render or plain as appropriate:
main = do
r <- terminalRenderer
T.putStrLn $ r $
"This will be escaped as "
<> red "red"
<> " only if we're connected to a tty."
Development & Testing
stack setup
stack build --pedantic test
See also the Makefile.