Joe Marshall's essay is very good, but if you want to start from something simpler consider http://www.phyast.pitt.edu/~micheles/scheme/TheAdventuresofaPythonis

Joe Marshall's essay is very good, but if you want to start from something simpler consider http://www.phyast.pitt.edu/~micheles/scheme/TheAdventuresofaPythonistainSchemeland.pdf http://www.phyast.pitt.edu/~micheles/scheme/TheAdventuresofa...