Common Lisp Progress

The backstory: I'm trying to learn Common Lisp. It's sort of an arcane programming language with a few aspects that I rather like, and I'm viewing this as an exercise to generalize my programming experience/knowledge.

I've written some common lisp over the years, mostly because I use stumpwm, but I've been struggling to find a good project to start on my own or hack on an existing project.

A few weekends ago, I started hacking on coleslaw, which is a static site generator written in common lisp. The reasons are simple:

  • I know something about the static site generator domain, so I'm only trying to learn one thing.
  • Coleslaw is typical in many respects of site generators, but the architecture makes sense, and it's reasonably simple and hasn't been overly optimized.

There are three features I'm interested in adding:

  1. I want make it so that Coleslaw builds content incrementally: there's no reason that programs like this should have to rebuild all content on every build. There are two missing concepts "which pages changed," and "if one page changes, what other pages must change."
  2. I want to make the entire build process more configurable. Thise includes expanding the options that are available in the site configuration, and allowing users to define and edit themes within their projects.
  3. It feels wrong to leave the program signally threaded, particularly when build systems are inherently parallel, and Common Lisp real threads.
  • I want to make this blog more blog-like. The current site works fine, but I'm growing restless, and I want to explore more.

So I began hacking and managed to learn a lot about the codebase, and am getting into the swing of this project. I played with a naive concurrency approach but it didn't stick. For about a day of work, I:

  • Made the docutils package usable from coleslaw and fixed some issues there. See pull request.

  • Added a lot of configuration and made more things customizable. Pull requests.

    There's a lot of little things that I like or feel like I will shortly like, but the sticking points at the moment are:

  • A lot of things have started to make sense. let forms feel very natural. The object system is pretty great. I feel comfortable with the organization of code within a function. I don't mind the parentheses.

  • I remain pretty confused by the variable binding system outside of the basic let forms. I'm never sure about setf and setq (my policy thus far has just been to setf and troubleshoot if it doesn't do what I want.) If Python is all about the power of the namespace, it feels like CL is all about the power of scopes and I haven't yet learned all of them.

  • Oddly, conditionals feel really hard and cumbersome. The if form is more limited and not particularly clear, cond is pretty useful but often feels like a sledge hammer. unless, and when are clear but not perfect.

I've not found the idiomatic way to perform "set a variable to the return of a function if it's current value is 0/null/false, otherwise pass" which I find myself reaching for pretty frequently (and awkwardly.)

More to come, I'm sure!

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