hellerbarde

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

esmooov

The Secret Passions of Git Checkout

---

The Hand of God

Git checkout can do almost anything ... or, at least, many things. It can switch branches. It can mix and match branches. It can resolve merge conflicts. It can give you a scratchpad to test things. It can even be used to interactively patch files. It's so powerful because it's so abstract. But much like numinous mystics, abstraction makes it confusing.

Basically git checkout does two things:

danveloper

public class TrampolineLambda {
    interface TrampolineFunction<T, R> {
        R apply(T...obj);

        public default Object trampoline(T...objs) {
            Object result = apply(objs);
            if (!(result instanceof TrampolineFunction)) {
                return result;
            } else {
                return this;

rxaviers

People

:bowtie:	😄 :smile:	😆 :laughing:
😊 :blush:	😃 :smiley:	☺️ :relaxed:
😏 :smirk:	😍 :heart_eyes:	😘 :kissing_heart:
😚 :kissing_closed_eyes:	😳 :flushed:	😌 :relieved:
😆 :satisfied:	😁 :grin:	😉 :wink:
😜 :stuck_out_tongue_winking_eye:	😝 :stuck_out_tongue_closed_eyes:	😀 :grinning:
😗 :kissing:	😙 :kissing_smiling_eyes:	😛 :stuck_out_tongue:

andrewlkho

GPG subkeys marked with the "authenticate" capability can be used for public key authentication with SSH. This is done using gpg-agent which, using the --enable-ssh-support option, can implement the agent protocol used by SSH.

Requirements

A working gpg2 setup is required. It may be possible to use gpg 1.4 but with gpg-agent compiled from gpg2. If you are using OS X 10.9 (Mavericks) then you may find the instructions [here][1] useful.

jdegoes

class Option<A> {
  protected Option() { }
}
interface App<F, A> {
  F proof();
}
class OptionF  {
  private OptionF() {}
  
  private static class AppOption<A> implements App<OptionF, A> {

jdegoes

Applied Functional Programming with Scala - Notes

Copyright © 2016-2018 Fantasyland Institute of Learning. All rights reserved.

1. Mastering Functions

A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.

val square : Int => Int = x => x * x

djspiewak

Getting Started in Scala

This is my attempt to give Scala newcomers a quick-and-easy rundown to the prerequisite steps they need to a) try Scala, and b) get a standard project up and running on their machine. I'm not going to talk about the language at all; there are plenty of better resources a google search away. This is just focused on the prerequisite tooling and machine setup. I will not be assuming you have any background in JVM languages. So if you're coming from Python, Ruby, JavaScript, Haskell, or anywhere…  I hope to present the information you need without assuming anything.

Disclaimer It has been over a decade since I was new to Scala, and when I was new to Scala, I was coming from a Java and Ruby background. This has probably caused me to unknowingly make some assumptions. Please feel free to call me out in comments/tweets!

One assumption I'm knowingly making is that you're on a Unix-like platform. Sorry, Windows users.

Getting the JVM

Brainiarc7

Tuning Intel Skylake and beyond for optimal performance and feature level support on Linux:

Note that on Skylake, Kabylake (and the now cancelled "Broxton") SKUs, functionality such as power saving, GPU scheduling and HDMI audio have been moved onto binary-only firmware, and as such, the GuC and the HuC blobs must be loaded at run-time to access this functionality.

Enabling GuC and HuC on Skylake and above requires a few extra parameters be passed to the kernel before boot.

Instructions provided for both Fedora and Ubuntu (including Debian):

Note that the firmware for these GPUs is often packaged by your distributor, and as such, you can confirm the firmware blob's availability by running:

dfarquharson

Let us begin with a proof by contradiction. Suppose that programming languages don’t matter, so long as they’re Turing complete. Once the minimum mechanism of arbitrary computation has been satisfied, all languages are essentially the same, insofar as they are able to express all computable things. Now, suppose I ask you to write me an CRUD app in x86 assembly. I imagine that you would refuse this task, on the grounds that the choice of language would make the task unnecessarily painful, to the point of being intractable, even though the language is technically capable of eventually completing the job. Choosing a different language, such as Python or Java, would make this task significantly more bearable. The instant that we start choosing different languages for different problems we commit ourselves to the position that programming languages do indeed matter. If they didn’t, we would have no qualms with this task, and we would spend our days happily programming in machine code. Believing that Turing complet