Spectrum.hs 🎨

Colorful Terminal Output in Haskell (Work in Progress)

Spectrum gives you a simple way to add color and style to your Haskell terminal output. It's a port of the OCaml Spectrum library.

It's still under development and considered experimental at the moment, so expect breaking changes for the next few releases.

• That said, feel free to experiment with it and contribute (I can use the extra hands)!

Key Features:

• Full Color Support: Support for 8-Bit, 256-Color, and TrueColor
• Named Colors: Easily apply colors using keywords like red, green, blue, etc. For example the following prints bold yellow text:

putStrLn $ yellow $ bold "Bold Yellow"

• Styles: Support for most ANSI text styles, such as bold, italic, underline, blink,Inverse, etc.
• RGB and Hex Colors: Support for specifying colors using RGB values and hexadecimal codes.
• Background Colors: Set background colors using functions like bgRed, bgGreen, etc.
  • Note: Subject to change with upcoming releases -- see "Known Issues" below
• Automatic Color Detection: Adapts to different terminal capabilities and CI environments.

Installation:

You can install Spectrum.hs using either cabal or stack:

Using Cabal:

1. Add the dependency to your cabal file:

   dependencies:
     - Spectrum

2. Run cabal install

Using Stack (Recommended):

1. Add the dependency to your stack.yaml file:

   dependencies:
     - Spectrum

2. Run stack build

Usage:

Here's a basic example of using Spectrum:

import Spectrum.Colors

main :: IO ()
main = do
  putStrLn $ red "This text is red!"
  putStrLn $ bold $ blue "This text is bold and blue!"
  putStrLn $ rgb 255 0 0 "This text is red using RGB!"
  putStrLn $ hex "#00FF00" "This text is green using hex!"

Testing

You can run a quick sanity test by building the library using:

stack build

And then running Main.hs using:

stack exec spectrum-hs-exe

Ideally you should see a test page print out.

Known Issues and Limitations:

• Bugs: The library is still a WIP, mostly cobbled together over a few 3AM nights -- so expect alot of bugs as I work out a few the issues.
  • Foreground and Background: There's not an easy way to set a separate foreground and background color on the same text -- Ideally in the next release this will be ironed out, as i'm writing a few functions to make this easier to do.
  • Broken Hex and RGB Colors: The parsing logic for converting HEX to RGB isn't working for some reason (colors are hard, man) but I should have a fix for that soon.
• Experimental Features: Some features like ANSI Code 21 "Double Underline" (You should be able to find it under "ECMA-48 Select Graphic Rendition" in the man pages) are experimental and may not work as expected in all terminals.
  • Tested and working in Wezterm
  • Partially working in Kitty
  • Other terminals are untested at this time.
• Performance: Performance hasn't been tested thoroughly yet.
  • However I would like this to be able to be able to perform well when styling massive amounts of cloud logs, so performance improvements are definitely on the roadmap.
• Documentation: I'll be sure to put out more documentation as I continue working on the library -- in the meantime, feel free to send me a message with any questions you have.

Roadmap

• Fixes for Hex and RGB Rendering
• Additonal support for the pipe ▷ operator at some point -- so one can use (for example) putStrLn ▷ red ▷ bold "Bold Red Text" if they wish.
• Additional support for the original Spectrum syntax
• Performance Improvements

Contributing:

Contributions are welcome! Please feel free to open issues or submit pull requests.

License:

MIT

Disclaimer:

This library is a work in progress and is provided as-is. Use at your own risk! (aka not in production)