This are some experiments based on the ICFP 2006 competition.

See http://www.boundvariable.org/ for more information (and a paper about the goals of the competition).

Nothing fancy there, mostly a simple implementation of a VM with some interestig properties.

Besides the VM itself, what was interesting for me was the debugging phase that I had to go through when developping the VM. Debugging is no fun and the absence of a REPL or any kind of runtime VM inspector was really "annoying". I therefore developed some kind of a debugger, with a simple language associated to it. The VM can be run from within the debugger by adding the parameter "-d" to the command line.

What the debugger allowed me to play with (very simple stuff):

• parser / stack based interpreter for the debugger command line. It runs a simple VM also that interprets the command. The command is manually parser through a simple recursive descent parser (bad one), and the opcode stack is built through a simple post-order traversal of the parse tree

• buddy memory allocator (http://en.wikipedia.org/wiki/Buddy_memory_allocation)

• simple garbage collector

• Schorr / Waite tree traversal