How to profile a Haskell program

Just jotting down my notes whilst profiling one of my helper scripts. It would be great if the community could transform this into a tutorial

The case study

I have a script that converts from an XML format to some pickled data structures via Data.Binary. The XML part is generated by HaXml's DtdToHaskell. On a 54M XML file, the thing swaps like crazy and takes several hours. I would like to improve the situation.

Setting things up

Enable profiling on libraries

For example, my script uses HaXmL, which uses a library called polyparse:

cd polyparse
runhaskell Setup.hs configure --enable-library-profiling
runhaskell Setup.hs build
sudo runhaskell Setup.hs install
cd ..

cd HaXml
runhaskell Setup.hs configure --enable-library-profiling
runhaskell Setup.hs build
sudo runhaskell Setup.hs install

Enable profiling on your stuff

Note that I assume you are using Cabal. If not, see How to write a Haskell program. It's super easy, and you'll be happy you did it.