I’ve been hacking on a secret project that I’ve had in the works since, oh grief, the first check-in was:

<code>commit ccb93ca5f2b256babfa0f2ef9110ac0ac4019527
Author: Elf M. Sternberg <elf.sternberg@gmail.com>
Date:   Mon Feb 4 23:03:01 2013 -0800
Initial check-in for Scarlett.</code>

The original project (yes, it’s named “scarlett”, deal with it) was in a combination of Python and Javascript, with Backbone as the front-end. It was, quite frankly, a terrible project, but it did what I wanted it to: it kept track of my notes. I have a directory named “Wiki” into which I dump markdown files, and have for years, and all it does is give me a slightly better UI for ‘grep,’ but it’s better than nothing.

Lab notes for the first two weeks of January.

I’ve been fiddling with a branch of the PamSeam project named Lattice in an effort to streamline the base and speed up the runtime. There are three algorithms enabled and all of them have similar processes. The basic engine is also very slow, with lots of large allocations and copying the image over and over.

"You are responsible for explicitly understanding the rest of the program." A sentence like this appears in every tutorial explaining first-class continuations, a programming language construct that appears in Lisp, Scheme, and Haskell, and if you look at people discussing them they find such constructs "scary."

One of the things I did many, many moons ago was write a couple of small Lisp interpreters. (It was long enough ago that I'm sorry to say they were written in CoffeeScript.) One thing that I did finally understand while building these was how continuations could be used to replace almost all flow control, that if, while, and even function calls were all just specialized versions of continuations.

The problem with continuations is that they do look scary. But while watching Alexis King's awesome presentation Demystifying Delimited Continuations, I'm glad to say that I finally wrapped my head around the notation for continuations in a way that clarifies that terrifying sentence you find in every explanation of continuations, "A continuation is the code you write that will handle the rest of the program."