Patrick the purple dragon

dragoncoder047’s blog

random thoughts about nonrandom things

Recent articles...

Reverse-Engineering the Feedback 360

By dragoncoder047

Some time ago I ordered one of Parallax’s “Feedback 360” servos for a robotics project I’m working on. I wrote a little arduino library to control it, and it works well.

As-is, however, the servo itself is too big to fit where I want it to. I’m …


By dragoncoder047

Today I did a little more work on my programming language TEHSSL. And in testing it, I discovered some anomalies.

The first one is that – because of a typo on my part – testing TEHSSL will occasionally segfault when it tries to print the type of the “next” object after freeing …


By dragoncoder047

I started writing a new programming language, TEHSSL, a few days ago. Starting from scratch (again!) wasn’t easy, and I’m nowhere near done yet. I have got two things working so far: the garbage collector, and the tokenizer. I have no idea how to handle the glue in …

Some Unrelated Ideas

By dragoncoder047

Immediately after I wrote the last post I stumbled upon the Cognate programming language. It is sort of a weird cross between Forth, Lisp, and Tcl, all at once, and I strangely like it. Currently Cognate is only implemented by a Cognate-to-C transpiler, so I won’t be able to …

Scratching My Head Again

By dragoncoder047

Again I find myself scratching my head over a simple scripting language. Yisp got way too complicated; tinyTcl leaked memory; and MicroPython can’t be extended with custom functions. All I want to do is have a scripting engine for my ESP32 that can run scripts off an SD card …


By dragoncoder047

C headers are annoying. I was getting fed up with uLisp/Yisp and so I decided to run another Google search for “embeddable scripting language for Arduino”.

It turned up mruby-arduino – poorly documented, and a little too big for my needs.

It turned up eLua – which unfortunately is just a …

Lisp Practice

By dragoncoder047

Today I decided I would have a little fun with Lisp. I wanted to try and make a program that you can type in a function and get a graph of it.

I started off with a function that takes an $x$-value and a list of coefficients, and evaluates …

uLisp Thoughts

By dragoncoder047

For a while I have been trying to work out some bugs in David Johnson-Davies’ uLisp interpreter for Arduinos. I ported some macro and quasiquote extensions for an older version of uLisp to the current version, and apparently I did not do something right – it crashes whenever I try to …

(Almost) No Javascript!

By dragoncoder047

I did a total redesign of my Langton’s Ant simulator last week – and most of the formatting I was able to do with pure CSS - no Javascript needed for layout control.

Previously I had a rather crude layout consisting of a fixed-size canvas and a textbox below it. The …

Two Down, A Zillion More To Go

By dragoncoder047

I have finally written code that actually compiled and ran on the little ESP32 board I bought, and I hate the blasted thing already.

For starters, the process is slow, annoying, and tedious:

  1. I click UPLOAD, and the Arduino IDE begins compiling by … dumping preferences.
  2. It then has to shuffle …

Page 1 of 3 Next> Last>>