Jaimy Emmanuel jemmanuel

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?

require-from-twitter

Since Twitter doesn't have an edit button, it's a suitable host for JavaScript modules.

How to use

Source tweet: https://twitter.com/rauchg/status/712799807073419264

const leftPad = await requireFromTwitter('712799807073419264');

Cryptographic Best Practices

Putting cryptographic primitives together is a lot like putting a jigsaw puzzle together, where all the pieces are cut exactly the same way, but there is only one correct solution. Thankfully, there are some projects out there that are working hard to make sure developers are getting it right.

The following advice comes from years of research from leading security researchers, developers, and cryptographers. This Gist was [forked from Thomas Ptacek's Gist][1] to be more readable. Additions have been added from

Key-Value Memory Networks for Directly Reading Documents

Introduction

Knowledge Bases (KBs) are effective tools for Question Answering (QA) but are often too restrictive (due to fixed schema) and too sparse (due to limitations of Information Extraction (IE) systems).
The paper proposes Key-Value Memory Networks, a neural network architecture based on Memory Networks that can leverage both KBs and raw data for QA.
The paper also introduces MOVIEQA, a new QA dataset that can be answered by a perfect KB, by Wikipedia pages and by an imperfect KB obtained using IE techniques thereby allowing a comparison between systems using any of the three sources.
Link to the paper.

Related Work

Who pays when startup employees keep their equity?

JD Maturen, 2016/07/05, San Francisco, CA

As has been much discussed, stock options as used today are not a practical or reliable way of compensating employees of fast growing startups. With an often high strike price, a large tax burden on execution due to AMT, and a 90 day execution window after leaving the company many share options are left unexecuted.

There have been a variety of proposed modifications to how equity is distributed to address these issues for individual employees. However, there hasn't been much discussion of how these modifications will change overall ownership dynamics of startups. In this post we'll dive into the situation as it stands today where there is very near 100% equity loss when employees leave companies pre-exit and then we'll look at what would happen if there were instead a 0% loss rate.

What we'll see is that employees gain nearly 3-fold, while both founders and investors – particularly early investors – get dilute

	(ns firstshot.chessknightmove
	(:refer-clojure :exclude [== >= <= > < =])
	(:use clojure.core.logic
	clojure.core.logic.arithmetic))

	(defn knight-moves
	"Returns the available moves for a knight (on a 8x8 grid) given its current position."
	[x y]
	(let [xmax 8 ymax 8]
	(run* [q]

	function certchain() {
	# Usage: certchain
	# Display PKI chain-of-trust for a given domain
	# GistID: https://gist.github.com/joshenders/cda916797665de69ebcd
	if [[ "$#" -ne 1 ]]; then
	echo "Usage: ${FUNCNAME} <ip\|domain[:port]>"
	return 1
	fi

	local host_port="$1"

	enum { BMAX = 32, BMIN = BMAX / 2, BHEIGHT = 6 };

	struct BNode {
	uint32_t length;
	Key keys[BMAX];
	union {
	BNode *children[BMAX];
	Value values[BMAX];
	};
	};

	man() {
	env \
	LESS_TERMCAP_mb=$(printf "\e[1;31m") \
	LESS_TERMCAP_md=$(printf "\e[1;31m") \
	LESS_TERMCAP_me=$(printf "\e[0m") \
	LESS_TERMCAP_se=$(printf "\e[0m") \
	LESS_TERMCAP_so=$(printf "\e[1;44;33m") \
	LESS_TERMCAP_ue=$(printf "\e[0m") \
	LESS_TERMCAP_us=$(printf "\e[1;32m") \
	man "$@"