Re: [Haskell-cafe] Painting logs to get a coloured tree

2009/2/9 Joachim Breitner <mail@joachim-breitner.de>

Now while this works, and while ST is still somewhat pure, I'm wondering if there is no better way of expressing "This piece of information came from the point in a data structure, so something else can be put here easily".

You might want to look into zippers: http://haskell.org/haskellwiki/Zipper Luke