A weekly look back at Hacker News coding centric posts from 5 years ago.
Why I’m Betting on Julia by Evan Miller
493 points | 252 comments
In this post Evan talks about why Julia captured his attention, a reason he points isn’t one that the “language geeks” would have.
Normally I use one language to make something work, and a second language to make it fast, and a third language to make it scream. [..] Unfortunately, there’s a big wall in between the prototyping language and C, and another big wall between C and assembler. Besides having to learn three different languages to get the job done, you have to mentally switch between the layers of abstraction.
This is an excellent reason to choose a language, one that is often forgotten when we’re talking about the new shiny language.
Given Julia’s value proposition I do wonder why it remains an also ran alongside Matlab, R and Python. Certainly at Biarri we’ve talked about Julia on and off as an alternative to Python for our optimization software. However it has always been easier to pick up pypy or C++ rather than learn a new language, one that isn’t also geared to our web app use cases.
Perhaps it is because of library support as Evan suggested in 2014:
Julia’s only drawback at this point is the relative dearth of libraries
How Radians Work in 30 Seconds by Lucas V. Barbosa
474 points | 102 comments
Copyright 2013 Lucas V. Barbosa
I wish I had this animation in high school, I recall grasping the equations of radians long before I grasped them using first principles.
Commenter ronaldx points out in the top comment:
This is by LucasVB, who is prolific at animating math for Wikipedia: https://en.wikipedia.org/wiki/User:LucasVB/Gallery
His other works are also worth checking: http://1ucasvb.tumblr.com/ (for example, he has a super-nice explanation of Fourier series).
You can also follow Lucas on Twitter @LucasVB
Emacs, naked by Bastien Guerry
294 points | 194 comments
A run through on stripping out the default UI chrome from GNU emacs creating what I liken to Zen mode in other editors. I finally moved off of Emacs a couple of years ago to standardize on the editor the rest of the team at Biarri was using, which was Sublime and now Code. I’ve utilized Zen modes in both editors, for example while writing this post. People remain passionate about Emacs & Vim while the rest of us bounce from editor to editor every couple of years, maybe they’ve got the right idea?
Follow Bastien on Twitter @bzg2
Use Subqueries to Count Distinct 50X Faster by Periscope Data
289 points | 98 comments
A clever technique for a common problem we all need to solve from time to time.
What stands out in this post is the inclusion of some nice psql
EXPLAIN diagrams to help us picture the query plans. If found that despite
not having a deep understanding of the PostgreSQL query planner I could follow
the reasoning behind the performance improvements.
You’ll want to keep this caveat in mind if you apply this technique however.
As always, data size and shape matters a lot. These examples benefit a lot from a relatively low cardinality. There are a small number of distinct (user_id, dashboard_id) pairs compared to the total amount of data. The more unique pairs there are — the more data rows are unique snowflakes that must be grouped and counted — the less free lunch there will be.
Follow Periscope Data on Twitter @PeriscopeData
Code is not Literature by Peter Seibel
240 points | 84 comments
I have been inspired to “read” code-bases from time to time, often when re-visiting The Architecture of Open Source Applications but I’ve never managed it in any meaningful way. In this post Peter Seibel explains why that is and what strategies you could employ to succeed at this activity and what the value of the exercise is.
Code is not literature and we are not readers. Rather, interesting pieces of code are specimens and we are naturalists. So instead of trying to pick out a piece of code and reading it and then discussing it like a bunch of Comp Lit. grad students, I think a better model is for one of us to play the role of a 19th century naturalist returning from a trip to some exotic island to present to the local scientific society a discussion of the crazy beetles they found: “Look at the antenna on this monster!
Follow Peter on Twitter @peterseibel