Ok, I actually do not really know if my machine is spineless or tagless, but it certainly reduces graphs.
This is my attempt to Implementing lazy functional languages on stock hardware: the Spineless Tagless G-machine by Simon L. Peyton Jones, where the stock hardware is PHP. The mechanics in this implementation are a little different from the mechanics described in the paper, which targets C. Thus i especially handle namespacing, jumps and the heap a little different. Garbage collection and pointer managment is mostly done by PHP. I also tried to implement my machine in a way that uses no globals but a STG object instead. Most of the concepts outlined in the paper should be recognizable still. This is for my fun and education, and hopefully yours too.