Handles colors and special effects for text. Internally this module uses the Haskell terminfo library, which links against the UNIX library of the same name, so it should work with a wide variety of UNIX terminals.

The building block of Rainbow is the Chunk. Each Chunk comes with a TextSpec, which specifies how the text should look on 8-color and on 256-color terminals. The Chunk is a full specification; that is, although Chunks are typically printed one after the other, the appearance of one Chunk does not affect the appearance of the next Chunk.

You have full freedom to specify different attributes and colors for 8 and 256 color terminals; for instance, you can have text appear red on an 8-color terminal but blue on a 256-color terminal.

Some useful combinators are provided to assist with the building of Chunks. plain builds a Chunk with a provided Text that is rendered using the terminal's default settings and colors. You then use +.+ to combine different modifiers to change how the Chunk is rendered. Here's an example:

 {-# LANGUAGE OverloadedStrings #-}

 -- This chunk is blue and underlined, both on 8-color and 256-color
 -- terminals.
 blueHello :: Chunk
 blueHello = plain "Hello world!" +.+ f_blue +.+ underline

 -- This chunk is red on 8-color terminals but uses color 88 on
 -- 256-color terminals. Because +.+ is left-associative, the
 -- color256_f_88 supersedes the f_red, which sets the foreground
 -- on both 8 and 256 color terminals to red.
 redHello :: Chunk
 redHello = plain "Hello world!" +.+ f_red +.+ color256_f_88

 -- This chunk is underlined on 8-color terminals but is not
 -- underlined on 256-color terminals.
 underlinedOn8 :: Chunk
 underlinedOn8 = plain "Hello world!" +.+ underline8

 newline :: Chunk
 newline = plain "\n"

 -- How to print all these chunks
 main :: IO ()
 main = do
   t <- termFromEnv
   printChunks t [blueHello, nl, redHello, nl, underlinedOn8, nl]

These modifiers affect both 8 and 256 color terminals:

 {-# LANGUAGE OverloadedStrings #-}
 underlinedOn8and256 :: Chunk
 underlinedOn8and256 = plain "Underlined!" +.+ underline

There are also modifiers to turn an effect off, such as boldOff. Ordinarily you will not need these because each chunk starts with no effects, so you only need to turn on the effects you want. However the off modifiers are here if you need them.

These modifiers affect 8-color terminals only. For instance this appears bold only on an 8-color terminal:

 {-# LANGUAGE OverloadedStrings #-}
 boldOn8 :: Chunk
 boldOn8 = plain "Bold on 8 color terminal only" +.+ bold8

These modifiers affect 256-color terminals only. For instance, this text is underlined on 256 color terminals but is bold on 8-color terminals:

 {-# LANGUAGE OverloadedStrings #-}
 underlinedOn256 :: Chunk
 underlinedOn256 = plain "Underlined on 256 color terminal"
                 +.+ underlined256 +.+ bold8

These color modifiers affect both 8 and 256 color terminals. For example, to print something in red on blue on both an 8 and a 256 color terminal:

 {-# LANGUAGE OverloadedStrings #-}
 redHello :: Chunk
 redHello = plain "Hello world!" +.+ f_red +.+ b_blue

The color names assume a palette similar to the default one that xterm uses.

The color names assume a palette similar to the default one that xterm uses.

A style is a bundle of attributes that describes text attributes, such as its color and whether it is bold.

Ordinarily you shouldn't need to use these types but they are here in case they are useful; in particular, you can use them to examine a Chunk's TextSpec to see what its characteristics are.

Ordinarily you will not need the things down here. Instead, the definitions above will give you an instance of Mod that will create the effect or color you need.

Definitions are provided above that give you every possible color; however, these constructors are exported in case you want to make your own colors instead. Use at your own risk, as you can create non-sensical colors with this (such as 256-color colors in a Background8.)