edmundsmith

Method for Emulating Higher-Kinded Types in Rust

Intro

I've been fiddling about with an idea lately, looking at how higher-kinded types can be represented in such a way that we can reason with them in Rust here and now, without having to wait a couple years for what would be a significant change to the language and compiler.

There have been multiple discussions on introducing higher-ranked polymorphism into Rust, using Haskell-style Higher-Kinded Types (HKTs) or Scala-looking Generalised Associated Types (GATs). The benefit of higher-ranked polymorphism is to allow higher-level, richer abstractions and pattern expression than just the rank-1 polymorphism we have today.

As an example, currently we can express this type:

pamolloy

Wireguard + VXLAN demo

Scripts to confgire a group of hosts on a LAN to use VXLAN over Wireguard.

Wireguard routing

• Making your own private Internet
• VXLAN & Linux
• Bridge vs Macvlan
• iproute2 bridging

s8sg

Create Bridge interface on the host and give internet access

sudo ip link add name br0 type bridge
sudo ip addr add 172.20.0.1/24 dev br0
sudo ip link set dev br0 up
sudo sysctl -w net.ipv4.ip_forward=1
sudo iptables --table nat --append POSTROUTING --out-interface enp3s0 -j MASQUERADE
sudo iptables --insert FORWARD --in-interface br0 -j ACCEPT

Create a tap device and link to the bridge

vcarl

const userTiming = () => (next) => (action) => {
  if (performance.mark === undefined) return next(action);
  performance.mark(`${action.type}_start`);
  const result = next(action);
  performance.mark(`${action.type}_end`);
  performance.measure(
    `${action.type}`,
    `${action.type}_start`,
    `${action.type}_end`,
  );

gaearon

Note:

When this guide is more complete, the plan is to move it into Prepack documentation.
For now I put it out as a gist to gather initial feedback.

A Gentle Introduction to Prepack (Part 1)

If you're building JavaScript apps, you might already be familiar with some tools that compile JavaScript code to equivalent JavaScript code:

• Babel lets you use newer JavaScript language features, and outputs equivalent code that targets older JavaScript engines.

Diggsey

Looking into the Future

futures-rs is the library which will hopefully become a shared foundation for everything async in Rust. However it's already become renowned for having a steep learning curve, even for experienced Rustaceans.

I think one of the best ways to get comfortable with using a library is to look at how it works internally: often API design can seem bizarre or impenetrable and it's only when you put yourself in the shoes of the library author that you can really understand why it was designed that way.

In this post I'll try to put down on "paper" my understanding of how futures work and I'll aim to do it in a visual way. I'm going to assume you're already somewhat familiar with Rust and why futures are a useful tool to have at one's disposal.

For most of this post I'll be talking about how things work today (as of September 2017). At the end I'll touch on what's being proposed next and also make a case for some of the changes I'd like to see.

If you're interested in learning more ab

nlinker

use std::marker::PhantomData;
use std::cell::Cell;

pub struct Game<'g> {
    // Putting the lifetime 'g into a PhantomData<Cell<&'g ()>> instead of a
    // PhantomData<&'g ()> makes 'g invariant instead of covariant.
    // I don't know if that's necessary here, but better be safe than sorry.
    // See https://doc.rust-lang.org/nomicon/subtyping.html for more info.
    phantom: PhantomData<Cell<&'g ()>>,
}

paulirish

// see for screenshot:
//     https://twitter.com/paul_irish/status/829090506084749312 

const http = require('http');

function requestHandler(request, response) {
	const headers = {
		'Server-Timing': `
		  sql-1;desc="MySQL lookup Server";dur=100,
		  sql-2;dur=900;desc="MySQL shard Server #1",

caraboides

#!/bin/sh
set -e
HOST=localhost
DB=test-entd-products
COL=asimproducts

S3PATH="s3://mongodb-backups-test1-entd/$DB/$COL/"
S3BACKUP=$S3PATH`date +"%Y%m%d_%H%M%S"`.dump.gz
S3LATEST=$S3PATH"latest".dump.gz
/usr/bin/aws s3 mb $S3PATH

paulirish

A few conversations have circled around user-side structural profiling. For context, see React PR #7549: Show React events in the timeline when ReactPerf is active

One particular concern is the measurement overhead. This gist has a benchmarking script (measure.js) for evaluating overhead and initial results.

Results: performance.mark()

Runs about 0.65µs per mark() call. Naturally, that's ~= an overhead of 1ms for 1500 mark()s.