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Sunday, December 3, 2017

Code speed is overrated

Premature optimization is the root of all evil.
        -- Donald Knuth

I see a lot of arguments about which language or techniques are faster, with some quite heated discussion, and a lot of effort tweaking code to make it faster. As much fun as these may be, they are largely irrelevant to the working programmer.

Thursday, November 2, 2017

Why you should be afraid of the Internet of Things

I first became excited about what eventually became the Internet of Things (aka IoT) back in the early 90s, after I wrote my first web server. I realized it was no more complex than a telnet server, so could easily replace the telnet servers in the few networked devices we had then. So we'd have point and click web configuration for those devices that was friendly and easy to use and that idea was just cool. These days, I'm mostly afraid of it.

Sunday, July 23, 2017

Some ZFS speed tests


I just got my first new desktop in long enough that it's the first one with SSDs. Those were large enough that I had a lot of space for level 2 archive replacement cache (L2ARC) for the spinning data drives. It also had an M2 slot, so I could add a small device as a separate intent log (SLOG), neither of which I had used before. Finally, I'm moving to a new operating system (Ubuntu from FreeBSD), so it seemed like a good time to do some disk benchmarks.

Sunday, June 25, 2017

Introduction to Lifetimes in Rust


A language that doesn't affect the way you think about programming is not worth knowing.
    -- Alan J. Perlis
Rust enhances it's variables with lifetime information, which I believe is unique among languages currently in production. This is the most exciting and best language feature I've encountered since recursion. It makes me think about aspects of a program I wasn't thinking about before and catches heisenbugs at compile time. I hope that explaining that to you will help you catch that excitement.

Wednesday, May 11, 2016

A first look at Rust

What is Rust?

Rust is one of the crop of system languages that target roughly the same space as C: running on bare metal, system utilities and libraries, and applications. Like most of them, it incorporates features from the last half century of language research - modern macros, algebraic data types, type inference, user-controlled polymorphism, variable sized arrays, and some degree of inheritance. I think it made a nice set of choices, but that's honestly more a matter of taste than anything else. I'll look at those in some detail, and explain why you'd want to learn Rust.

What sets Rust apart from other such languages is that the compiler also keeps track what code can read and write an object, which it refers to as the lifetime of the object. It uses that to prevent you from creating multiple references that can change an object. This changes how you program in a number of ways.

Wednesday, October 7, 2015

A close look at pwm input


PWM is used for things like controlling servos, motors and LEDs. Output from a micro-controller is easy, and the hardware usually handles it. Remote control receivers also output it, as they are used to control these things as well. RC transmitters often output the closely related PPM (aka CPPM). It's not unusual to want to read those values with an Arduino microcontroller, but this is not as easy, as common - meaning ATmega328 and similar - hardware doesn't do it directly. So let's look at some options to do that.

Monday, August 10, 2015

Unicode input with X11


Whether you like it or not, Unicode is here. Modern programming languages allow it to be used in variable names and for operator symbols, older ones are adding it as extensions, and inputting it is getting easier all the time.
And frankly, I think most of us would rather read x ≠ 23 instead of x /= 23 or x != 23 or even x =/= 23 . Or how about x ∈ A instead of element(x, A)?
So here's how I set up my X11 keyboard to allow me to input the more popular programming symbols - at least for Haskell - directly from the keyboard, without having to use some editor-specific magic.