Naming Things Poorly

computer scientists have a very unfortunate way of naming things. Take S-expressions for example. They’re pretty a fundamental notation method for functional programming. I was re-implementing a variant of it recently, and obviously I named the package sexp

Part of the implementation I wrote was that I had a “shortcut” way of representing the S-expressions internally – as slice (called List) and atoms, instead of actually making a linked-list (because child node access was faster, given that most of the trees are static). But sometimes typos happen, and when they do, they read so awfully:


func join(s sexp.Sexp) error {
...
for _, child := range sList {
childList := child.(sex.List)
}
}



On Buying A New Vacuum Cleaner

Just happened.

Her:

Ooh, Dyson is on sale!

Me:

Yeah, no. Dyson sucks.

Her:

Me:

Er, I mean, Dyson doesn’t suck.

Her:

We’re buying a Miele instead. Because Miele vacuum cleaners are awesome at sucking.

Holy Crap I’ve Got Abs (Kinda)

In the span of a year, I went from looking like the picture on the left to looking like the picture on the right.

This blog post is what I did to get there.

I went from 80kg at about 24% body fat to 65kg at about 14-15% body fat. Most of this blog post will indicate a much higher start point (of which I didn’t have a photo of), at 87kg and about 30% body fat.

YAGNI

This morning my computer crashed. So I rebooted it. I was in the midst of a project that had a lot of git branches (as I was working on competitive ideas to see which version would work best), and I couldn’t recall which branch I was on.

I thought it would be a good time to update my .bashrc file to perhaps add a git status to my bash prompt. Afterall, there are some pretty nice prompt string hacks for git out there.

And so I started to edit my .bashrc file. I opened it, and I discovered that I have over 20 aliases and functions that I created, and I haven’t used any of them in the last 2 years. Heck, over the years, I even went from a colourful prompt to a black and white prompt!

I used to have fancy dotfiles for most of my things, but now I use mostly default stuff. It makes portability much easier – I can work on any station without having to bother much about the configs.

I think the YAGNI approach works best. You Ain’t Gonna Need It when it comes to adornments for your computer. All you need is to be able to do work without extra distraction. Of course an argument could be made that having your prompt show your git status makes it unnecessary for you to git status everytime you start afresh on a new project. It really depends on how much time you have saved. The tradeoff for me constantly knowing my git status is not worth it.

What was worth it for me? This piece of code in my .bashrc file:


# http://stackoverflow.com/questions/21160386/trigger-a-command-when-cding-into-a-directory
function workspace_cd() {
cd \$@ && [ -f ".bashworkspace" ] && source .bashworkspace
}
alias cd="workspace_cd"



Other than that, nothing from the custom alert functions to the shortcuts for extracting files (turns out I just type tar -xzvf all the time anyway) were particularly used.

So I truncated my bashrc file to something like 50 lines. And… that’s enough yak shaving for the day.

An Apology

I made a mistake in posting a women-hostile picture on Twitter yesterday. This is an apology. But first, let’s start with a recap.

Yesterday I posted this tweet:

I first saw the picture on /r/funny. And I tweeted the picture after a brief view. I mainly tweeted the comic because I believe that politicking identity issues is generally a waste of time[1]. I had neglected to notice that it came from @AntiFemComics.

This morning, a shitstorm ensued. I woke up and the first notification was from Nick Coghlan:

Upon reading that, I went and re-read the comic. I realize the horror that I have in fact misread the comic. And the issue snowballed on. This blog post will stand as an official apology from me.

1. [1] Politicking of any issue is generally a waste of time, in my opinion.

Go Test Files Are Part of the Same Package

Just a quick one. I was working on improving performance for a certain method of mine. I had found the hot loop [1], and I wrote a few benchmark methods to test some ideas.

I was using the testing package’s benchmark function to benchmark the methods, and for a method, I had abstracted out some code so that it can run in a goroutine. Here’s the code for the function:


func receiver(ch chan tmp, out chan []float64, wg *sync.WaitGroup) {
Ys := make([]float64, len(x))
for v := range ch {
Ys[v.id] = v.res
wg.Done()
}
out <- Ys
}


Spotted the problem? No? It's the second line: retVal := make([]float64, len(x)). You'll note that x wasn't declared anywhere. And yet, the benchmarks ran! I only ran into a problem when I fed the test case a weird corner case where I knew funny things would happen.

At first I was puzzled why the compiler hadn't caught it. I scoured all through both files (it was a throwaway package, written solely to test ideas, so it had only two files: throwaway.go and throwaway_test.go)

Here are the top few lines of my throwaway_test.go file:


package throwaway

import (
"testing"
"math/rand"
)

var x []float64 = X(784) // <-- THE DECLARATION THAT CAUSED PAIN
func init() { ... }


I had added that variable originally as part of a setup/teardown function. I had then forgotten completely about it. I had been so used to writing code in the *_test.go files as if they were part of a separate package that just imported the functions, that I forgot that they were part of the same package.

The lesson learned today, other than global variables are evil[2], is that variables declared in the test files can have an effect on the main files if you're not careful about it, because the test files are part of the same package.

Now I want my hour lost back!

As Damian kindly points out:

The above only really happened because I was running go test -bench .  a lot. If I had used go build .  the compiler would have thrown an error

1. [1] pprof is an amazing godsend. The days of dicking around in valgrind or cProfile are long a memory of the past
2. [2] but sometimes are necessary, which I would argue for this specific test case, is

Whole Fruit Espresso

I’ve been toying around with new ideas of coffee lately. Here is one that I think went particularly well. It started with red-eyes: you put a shot of espresso in filter coffee, just to boost acidity and body of the coffee whilst still keeping the basic aromatics in the coffee (making espresso kills quite a bit of those).

I then moved on to the idea of making cascara red-eyes. If red eyes were flavourful, perhaps then using the pulp of the fruit will yield a different thing all together? And indeed it did. The hibiscus-y nature of the cascara tea does accentuate the espresso. Then I wondered if I could push it further – what if the cascara “tea” was made under pressure – i.e. espresso?

Intuitions From The Price Equation

George Price was a rather interesting fellow. A few months ago, I was reading a rather interesting piece about his life from HN. If you follow my blog posts (hello to the two of you), you’ll note that altruism and cooperative games is one of the things I like to blog about.

Following that article, I discovered the Price equation[1]. While grokking the equation, it had suddenly occurred to me that kin selection and group selection were indeed the same thing. It was a gut feeling, and I couldn’t prove otherwise.

I recently had a lot of time on hand[2], so I thought I’d sit down and try to make sense of my gut feel that kin selection and group selection were in fact the same thing. Bear in mind I’m neither a professional mathematician nor am I a professional biologist. I’m not even an academic and my interest in the Price equation came from an armchair economist/philosopher point of view. And so, while I grasp a lot of concepts, I may actually have understood them wrongly. In fact, just be forewarned that this entire post was a result of me stumbling around.

So, let’s recap what the Price equations look like (per Wikipedia):

$\Delta z = \frac{1}{w} cov(w_i, z_i) + \frac{1}{w} E(w_i \Delta z_i)$

Simply put, $\Delta z$ is the difference in phenotype between a parent population and the child population. And that difference is a function of two things:

1. The covariance of fitness and phenotype – $\frac{1}{w} cov(w_i, z_i)$ where $w$ is the average fitness of the population, $w_i$ is the individual fitness of $i$, and $z_i$ is the phenotype shared in the group.
2. The expected value of the fitness of the difference between the group’s phenotype and the parent group’s phenotype.
1. [1] Funny story. I was quite surprised I hadn’t heard of the Price equation, so I hit the books. I found the equation being referenced very very very very briefly in Martin Nowak’s Evolutionary Dynamics, and that was all
2. [2] Being laid off does that to you :)

The Skynet Argument Against Social Media

In The Terminator (1984), Skynet sends a T-800 to terminate Sarah Connor. And the Terminator had to look up a phone book to find three Sarah Connors, because it mainly didn’t know what Sarah Connor looked like or where she lived.

That made sense in 1984. If the records had been destroyed in the war – records can be destroyed because physical drives were expensive and don’t have much capacity. Skynet wouldn’t have known how Sarah Connor looked like, or any other of her personal details. Rewatching The Terminator in 2015, this would have made no sense. If Skynet were made today, it would simply scour the cloud for information about Sarah Connor. And she’d be cleanly terminated.

There you go, kids. Don’t use social media. Arnold Schwartzeneggar and the T-1000 will come kill you.