ezyang’s blog

the arc of software bends towards understanding

October, 2011

The new Reflections on Trusting Trust

In his classic essay Reflections on Trusting Trust, Ken Thompson describes a self-replicating compiler bug which is undetectable by source code inspection. The self-replication is made possible by the fact that most compilers are self-compiling: old versions of a compiler are used to compile new ones, and if the old version is malicious, it can […]

  • October 28, 2011

Obviously Correct

What do automatic memory management, static types and purity have in common? They are methods which take advantage of the fact that we can make programs obviously correct (for some partial definition of correctness) upon visual inspection. Code using automatic memory management is obviously correct for a class of memory bugs. Code using static types […]

  • October 24, 2011

Polyglot programming

Being back in town over MIT's Infinite Activities Period is making me think about what kind of short lecture I want to try teaching. I've been turning over the idea of a polyglot programming class in my head: the idea is that while most people feel really comfortable with only one or two programming languages, […]

  • October 12, 2011