In GHC 6.5 and subsequently you can import GHC as a Haskell library, which lets you write a Haskell program that has access to all of GHC. 

This page is a place for everyone to add
  * Notes about how to get it working
  * Comments about the API
  * Suggestions for improvement
and so on.

= Getting started =
You'll need to get a version of GHC that supports the GHC API.  Either download ghc from [http://www.haskell.org/ghc/docs/latest/html/building/sec-cvs.html CVS] or use darcs: {{{darcs get --partial http://darcs.haskell.org/ghc}}}.  There are also [http://www.haskell.org/ghc/dist/current/dist nightly snapshot distributions] available.

To use the GHC API you say simply 
{{{
  import GHC
}}}
Doing this imports the module `GHC` from the package `ghc`, which comes with GHC 6.5 and subsequent.  The module GHC exports the "GHC API", which is still in a state of flux.  Currently it's not even Haddock-documented.  You can see the source code (which is somewhat documented) here 
http://cvs.haskell.org/cgi-bin/cvsweb.cgi/fptools/ghc/compiler/main/GHC.hs

Here's an example main program that does it [attachment:Main.hs]