This module deals with the haddock and hscolour commands. Sadly this is
a rather complicated module. It deals with two versions of haddock (0.x and
2.x). It has to do pre-processing for haddock 0.x which involves
'unlit'ing and using -DHADDOCK for any source code that uses cpp. It
uses information about installed packages (from ghc-pkg) to find the
locations of documentation for dependent packages, so it can create links.
The hscolour support allows generating html versions of the original
source, with coloured syntax highlighting.