I wrote an article about the implementation of Hecl, posted here:

http://www.dedasys.com/articles/hecl_implementation.html

Originally it was for a magazine, but I decided that for the amount of money they could pay, I’d rather just have the freedom to post the article as widely as possible.

I think it might be of interest because Hecl is still a simple language, so those who don’t have the time or inclination to delve into the internals of a language like Tcl, Ruby or Erlang can still find out what goes into the making of an interpreter.