GHCi in colour

This page documents efforts to colourise GHCi output.

Example

Or a type error:

Output like this would be the result of running, for example:

   ghci --colour

and would appear in the console/xterm as ansi terminal coloured output.

Implementation

Using HsColour

An existing tool, HsColour, could be modified to operate interactively. In fact, HsColour is already interactive, and with a small patch added on 2006-12-14 to control ouput buffering better, this works relatively nicely:

   ghci 2>&1 | HsColour -tty

HsColour in action

There are small delays however, when lexing certain tokens, and the interaction with readline isn't ideal.

GuiHaskell

Neil Mitchell has a prototype gui haskell wrapper, based on gtk. Does this contain a reasonable ghci wrapper we could steal?

If you have an idea of how to do this nicely, add your proposal here.