Reading List

I’ve been doing some reading this weekend.  This post records a little of what I’ve learned.

The focus has been Scheme macros and separate compilation.  I’m trying to understand how a production quality Scheme system “should” be organized.  “Should” is in scare quotes because every Scheme user has at least one opinion on the topic, and no two seem to agree.

So here are the papers I’ve looked at in the last few days.

A Safer Scheme Interpreter, Part 3

In Part 1, I explained why my Scheme interpreter, Schetoo, has the ability to fail or restart any instruction.  In Part 2, I showed how it automatically checks that instructions do all necessary checks before they have any side effects.  Those two posts described raising exceptions with longjmp, but didn’t really explain how the interpreter catches exceptions.

A Safer Scheme Interpreter, Part 2

In my last post, I promised to explain how my Scheme interpreter, Schetoo, can automatically verify that its instructions are restartable.  But first, some background.

A Safer Scheme Interpreter

In the first half of 2010, I wrote a Scheme interpreter which I called Schetoo. It is a sequel to an interpreter called kbscheme, which I worked on off-and-on in 2008 and 2009. Both are written in C.

You can see them both on github.

https://github.com/kbob/kbscheme
https://github.com/kbob/schetoo

I undertook these projects to learn more about Scheme, interpreters, and garbage collection. Along the way, I came up with an interesting technique to make interpreter implementation less error-prone. That’s what I want to write about today.

Son of Scheme: Introducing Schetoo

I’ve started a new Scheme project. This one is called Schetoo. The name has connotations of “Scheme Two”, “me too”, and “Gentoo” (a hardcore Linux distribution and a breed of penguin).

A ‘blogger named Peter Michaux started a series in January called Scheme from Scratch. His goal was to write a very quick and dirty Scheme, just enough to bootstrap a Scheme compiler. I read his postings and decided to get started again.

Schetoo is similar in concept to my first Scheme, kbscheme. In fact, I reused a fair amount of code to get Schetoo up and running faster. But at the same time, I’m applying what I learned to try to get a better design.

I’ve published the code on GitHub.

http://github.com/kbob/schetoo

Scheme from Scratch

Peter Michaux has started a ‘blog series called Scheme from Scratch. He’s made ten posts so far. He’s developing a Scheme system incrementally, in tiny steps, so that it’s easy to read along and understand exactly what every bit of code does.

Recommended.

Scheme: Retrospective

The Scheme interpreter project is “on hold”. Maybe it’s “finished”. It’s time to take stock, see what I learned, what I accomplished, and what I could have done better.

Scheme project is on hold.

I’m officially putting my Scheme interpreter project “on hold” for a while. Progress has slowed to a virtual stop. It’s not because I’ve lost interest, but because I’m lost.

Simultaneously learning to think in Scheme, implementing hygienic macros through syntax-case, and (re)designing the core interpreter has proven to be too much. I haven’t been able to hack my way through it.

Someday I’ll pick the project up again. I’m still very interested in it. Maybe I’ll continue from the same code base, and maybe I’ll start over.

Scheme and Macro Expansion

I got to work on my Scheme interpreter this weekend.  Real life had interfered for about three weeks straight.

Scheme status

I’ve written here before about my efforts to write a Scheme interpreter from scratch.  The last update was in May, but I’m still working on it.  I’ve made 60 git commits since then.  The major thing I’m trying to do is implement macros, but I’m having a hard time of it.  No matter.  When they’re done, I’ll understand macros thoroughly.