travisbrown

The current version of this document is here.

This document contains additional supporting material for the claims in this post (published 1 September 2019), in response to a cease and desist letter from John De Goes that I received on 6 July 2020.

Please see also this post for more information about De Goes deleting the FCoP repository on GitHub shortly before sending the cease and desist letter.

Table of contents

• The complaints
• Response to complaint 1

wmayner

from IPython.display import Markdown, display

colors = ['#018700', '#00acc6', '#e6a500']

display(Markdown('<br>'.join(
    f'<span style="font-family: monospace">{color} <span style="color: {color}">████████</span></span>'
    for color in colors
)))

t3hnar

import cats.effect.Concurrent
import cats.effect.concurrent.{Deferred, Ref}
import cats.implicits._

trait Cache[F[_], K, V] {

  def getOrUpdate(k: K)(v: F[V]): F[V]

  def values: F[Map[K, Deferred[F, V]]]
}

johnynek

package org.bykn.list

import cats.Applicative

import cats.implicits._

/**
 * Implementation of "Purely Functional Random Access Lists" by Chris Okasaki.
 * This gives O(1) cons and uncons, and 2 log_2 N lookup.
 */

mpkocher

ssaavedra

#!/bin/sh
# Licensed under CC0 in jurisdictions where this is not directly in the Public Domain
# Authored by Santiago Saavedra (github.com/ssaavedra)


git scalafmt --test || exit 1

# If there are whitespace errors, print the offending file names and fail.
exec git diff-index --check --cached $against --

parente

Summary

nbconvert has a preprocessor that clears cell outputs from notebook files, leaving cell inputs intact.

Example

The following shell command reads my_input_notebook.ipynb, removes its cell outputs, prints the cleaned notebook to stdout, and redirects that output to a new notebook file named my_output_notebook.ipynb.

jupyter nbconvert my_input_notebook.ipynb --to notebook --ClearOutputPreprocessor.enabled=True --stdout > my_output_notebook.ipynb

holmberd

Setup GitHub repository SSH deploy keys

1. Create GitHub repository in github and save the SSH repository url

2. Init git on server in code directory

• git init

3. Create SSH keys on the server

• ssh-keygen -t rsa -b 4096 -C your@email.here
• Rename the key that doesn't end with .pub to repo-name.deploy.pem

djspiewak

Quick Tips for Fast Code on the JVM

I was talking to a coworker recently about general techniques that almost always form the core of any effort to write very fast, down-to-the-metal hot path code on the JVM, and they pointed out that there really isn't a particularly good place to go for this information. It occurred to me that, really, I had more or less picked up all of it by word of mouth and experience, and there just aren't any good reference sources on the topic. So… here's my word of mouth.

This is by no means a comprehensive gist. It's also important to understand that the techniques that I outline in here are not 100% absolute either. Performance on the JVM is an incredibly complicated subject, and while there are rules that almost always hold true, the "almost" remains very salient. Also, for many or even most applications, there will be other techniques that I'm not mentioning which will have a greater impact. JMH, Java Flight Recorder, and a good profiler are your very best friend! Mea

odersky

Principled Meta Programming for Scala

This note outlines a principled way to meta-programming in Scala. It tries to combine the best ideas from LMS and Scala macros in a minimalistic design.

• LMS: Types matter. Inputs, outputs and transformations should all be statically typed.

• Macros: Quotations are ultimately more easy to deal with than implicit-based type-lifting

• LMS: Some of the most interesting and powerful applications of meta-programming