Olov Lassus

Describing Live programming (again)

09 Oct 2011

It’s funny how the brain does context switching sometimes. You work really hard on something just to almost forget about it immediately after the release. You then let it be for a few years until you dare to open up that project or document again to figure out why you worked that hard on it in the first place.

Anyways. I wrote my master’s thesis in 2006 and I was really passionate about it at the time. I wanted to describe how to create a better programming environment than what we currently had without falling into the “everything has already been invented in good ol’ Smalltalk and the LISP machines” trap. I specifically focused on enabling the programmer to write and modify code at run-time, thus the name Live programming.

I was satisfied with what I accomplished. I had a prototype running that I used to test that the source code, AST and callstack transformations I described in the thesis were valid. I knew what the next step would be (post thesis) but I also knew that I didn’t have the time to invest into making a full blown implementation, so I let it be.

Almost six years has passed since then and the programming environments people use today haven’t changed much. I’m still passionate about Live programming. I figured it wouldn’t hurt to expose the concept to a new reader or two, thus this blog article.

When I wrote the thesis I was primarily interested in finding out how far I could take the concept. I picked JavaScript as the prototype language because it seemed to have momentum at the time and I guess that choice turned out well. I picked Narcissus because it was the simplest interpreter I could find. The prototype environment uses a heavily modified Narcissus (I turned it stackless/callstack-explicit) and it seems to have bitrot since then but I’ll see if I can beat the code into shape and release it out again if there’s any interest.

I still think that JavaScript is an excellent language for implementing a Live programming environment. I’d love to see one integrated directly in the browser, and also tied together with a node.js environment. It needs to be directly integrated with the JS impl, i.e. the V8, SpiderMonkey or what have you. It’s not a small feat.

So here we go: Describing Live programming using program transformations and a callstack explicit interpreter. Read chapter 1 and 2 for more info about Live programming. Read the other chapters only if you’re interested in how it works under the hood (the transformations).

Oh and I did an s/Johansson/Lassus thing in 2007, in case you wonder.

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