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cb372 /
Last active Mar 15, 2021
Category theory jargon cheat sheet

Category theory jargon cheat sheet

A primer/refresher on the category theory concepts that most commonly crop up in conversations about Scala or FP. (Because it's embarassing when I forget this stuff!)

I'll be assuming Scalaz imports in code samples, and some of the code may be pseudo-Scala.


A functor is something that supports map.

View git-squash
git rebase --interactive --autosquash \
$(git merge-base $(git symbolic-ref --short HEAD) master)
mikelehen / generate-pushid.js
Created Feb 11, 2015
JavaScript code for generating Firebase Push IDs
View generate-pushid.js
* Fancy ID generator that creates 20-character string identifiers with the following properties:
* 1. They're based on timestamp so that they sort *after* any existing ids.
* 2. They contain 72-bits of random data after the timestamp so that IDs won't collide with other clients' IDs.
* 3. They sort *lexicographically* (so the timestamp is converted to characters that will sort properly).
* 4. They're monotonically increasing. Even if you generate more than one in the same timestamp, the
* latter ones will sort after the former ones. We do this by using the previous random bits
* but "incrementing" them by 1 (only in the case of a timestamp collision).
kyleburton / bot-verbs.txt
Last active Apr 13, 2021
The list of 'bot-verbs' that we give to new team members.
View bot-verbs.txt
* writing lines of code is one of the least valuable things I can do
* cultivate your impatience
* reject the status quo, unless we can re-derive it from first-principles
* engineers imprint on the first languages (techniuqes, frameworks or technology) that we find success with (unconsciously seen as caregivers, which we defend w/o always knowing why)
* we tend to overvalue the familiar/known; we tend to undervalue the unfamiliar/unknown, this interferes with our receptiveness to new ideas and personal growth
* we're 90% composed of bad habits; many of our best habits become bad as time passes; this allows us to filter for the fundamental; the great
* make doing the right thing easier than any other thing, or we will fail to achieve greatness, or break bad habits
* be conscious, be intentional
* "is this the highest we can aim?" (I prefer this over "is this the best we can do", the former is aspirational, the latter is judgemental)
chengyin / linkedout.js
Last active Oct 2, 2020
Unsubscribe all LinkedIn email in "one click". For an easier to use version, you can check out the bookmarklet:
View linkedout.js
// 1. Go to page
// 2. You may need to login
// 3. Open JS console
// ([How to?](
// 4. Copy the following code in and execute
// 5. No more emails
// Bookmarklet version:

Build your own private, encrypted, open-source Dropbox-esque sync folder


  • One or more clients running a UNIX-like OS. Examples are given for Ubuntu 12.04 LTS, although all software components are available for other platforms as well (e.g. OS X). YMMV
  • A cheap Ubuntu 12.04 VPS with storage. I recommend Backupsy, they offer 250GB storage for $5/month. Ask Google for coupon codes.

Software components used:

  • Unison for file synchronization
  • EncFS for folder encryption
dustin / progress.go
Last active Dec 19, 2015
Uploading a ton of stuff to S3, I decided I wanted something that would take this boring *os.File and give me a progress indicator. Here's the thing I threw together. Sends this sort of thing to stdout ('\r'ing over itself every second): 10MB/72MB (14.6%)
View progress.go
package main
import (
pbailis /
Last active Apr 15, 2018
Quick and dirty (incomplete) list of interesting, mostly recent data warehousing/"big data" papers

A friend asked me for a few pointers to interesting, mostly recent papers on data warehousing and "big data" database systems, with an eye towards real-world deployments. I figured I'd share the list. It's biased and rather incomplete but maybe of interest to someone. While many are obvious choices (I've omitted several, like MapReduce), I think there are a few underappreciated gems.

###Dataflow Engines:

Dryad--general-purpose distributed parallel dataflow engine

Spark--in memory dataflow

mislav / OpenSSL
Last active May 9, 2019
Fix OpenSSL certificate errors on Ruby 2.0
View OpenSSL

The reason why you might get certificate errors in Ruby 2.0 when talking HTTPS is because there isn't a default certificate bundle that OpenSSL (which was used when building Ruby) trusts.

Update: this problem is solved in edge versions of rbenv and RVM.

$ ruby -rnet/https -e "Net::HTTP.get URI('')"
net/http.rb:917:in `connect': SSL_connect returned=1 errno=0 state=SSLv3
  read server certificate B: certificate verify failed (OpenSSL::SSL::SSLError)

You can work around the issue by installing a certificate bundle that you trust. I trust Mozilla and curl.

View gist:3217582
;; based on core.logic 0.8-alpha2 or core.logic master branch
(ns sudoku
(:refer-clojure :exclude [==])
(:use clojure.core.logic))
(defn get-square [rows x y]
(for [x (range x (+ x 3))
y (range y (+ y 3))]
(get-in rows [x y])))