Petter Aas petteraas

A vision for data interchange in Elm

How do you send information between clients and servers? What format should that information be in? What happens when the server changes the format, but the client has not been updated yet? What happens when the server changes the format, but the database cannot be updated?

These are difficult questions. It is not just about picking a format, but rather picking a format that can evolve as your application evolves.

Literature Review

By now there are many approaches to communicating between client and server. These approaches tend to be known within specific companies and language communities, but the techniques do not cross borders. I will outline JSON, ProtoBuf, and GraphQL here so we can learn from them all.

These are instructions for booting from an Ubuntu liveCD and installing NixOS on a machine. I needed to do this because the NixOS liveCD doesn't work on my machine (NixOS/nixpkgs#5829), so I'm just using the Ubuntu installation media as something to boot into.

Much of this is from discussion at NixOS/nixpkgs#14680.

Get the Ubuntu ISO: http://releases.ubuntu.com/16.04.1/ubuntu-16.04.1-desktop-amd64.iso

Write it to a USB drive with unetbootin

Comprehensions in Python the Jedi way

by Bjørn Friese

Beautiful is better than ugly. Explicit is better than implicit.

-- The Zen of Python

I frequently deal with collections of things in the programs I write. Collections of droids, jedis, planets, lightsabers, starfighters, etc. When programming in Python, these collections of things are usually represented as lists, sets and dictionaries. Oftentimes, what I want to do with collections is to transform them in various ways. Comprehensions is a powerful syntax for doing just that. I use them extensively, and it's one of the things that keep me coming back to Python. Let me show you a few examples of the incredible usefulness of comprehensions.

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

Clarify and agree on the scope of the system

User cases (description of sequences of events that, taken together, lead to a system doing something useful)
- Who is going to use it?
- How are they going to use it?

git commit stats

Commands to get commit statistics for a Git repository from the command line -
using git log, git shortlog and friends.

Most props on a JSX element are passed on to the component, however, there are two special props (ref and key) which are used by React, and are thus not forwarded to the component.

For instance, attempting to access this.props.key from a component (eg. the render function) is not defined. If you need to access the same value within the child component, you should pass it as a different prop (ex: <ListItemWrapper key={result.id} id={result.id} />) While this may seem redundant, it's important to separate app logic from reconciling hints.

	"""
	pybble.py

	Yup, you can run Python on your Pebble too! Go thank the good folks who
	made Transcrypt, a dead-simple way to take your Python code and translate
	it to very lean Javascript. In our case, instead of browser, we run it
	on Pebble using their equally dead-simple Online IDE and Pebble.js library.

	Here's a working example, it runs on a real Pebble Classic.

	""" Trains an agent with (stochastic) Policy Gradients on Pong. Uses OpenAI Gym. """
	import numpy as np
	import cPickle as pickle
	import gym

	# hyperparameters
	H = 200 # number of hidden layer neurons
	batch_size = 10 # every how many episodes to do a param update?
	learning_rate = 1e-4
	gamma = 0.99 # discount factor for reward

	#!/bin/bash

	#no PATH, no way to accidently run any programs
	PATH=''

	#useful variables
	term_height=0
	term_width=0
	term_scroll_height=0
	status_line_row=0