Felx inscapist

React - Functional error boundaries

Thanks to React hooks you have now happily turned all your classes into functional components.

Wait, all your components? Not quite. There is one thing that can still only be implemented using classes: Error boundaries.

There is just no functional equivalent for componentDidCatch and deriveStateFromError yet.

Proposed solution

Expression for a buildEnv-based declarative user environment

This is one way of managing your user profile declaratively.

Alternatives include:

an attrset-based nix-env-based environment, installed using nix-env -ir rather than nix-env --set. LnL has an overlay which shows a way of doing this.
home-manager, which provides NixOS-like config for your $HOME

Note that this is incompatible with regular imperative use of nix-env, e.g. nix-env -iA nixpkgs.hello. It has the advantage of allowing the installation of multiple outputs of the same package much better than nix-env's builtin profile builder does.

Configuring Emacs for react, es6, and flow

For a while, JSX and new es6 syntax had flaky support in emacs, but there's been huge work on a lot of packages. Using emacs for JavaScript with React, ES6, and Flow (or Typescript, etc) is really easy and powerful in Emacs these days.

This is how you can work on modern web development projects with full support for tooling like JSX, Flow types, live eslint errors, automatic prettier.js formatting, and more.

Set up `web-mode`

web-mode provides most of the underlying functionality, so a huge shout-out to the maintainer(s) there.

create-react-native-app purescript-app; cd purescript-app
pulp init --force
pulp build
src/Main.js

var React = require("react");
var RN = require("react-native");

exports.text = function(props){

Eric Elliott's "Composing Software" Series

A collection of links to the excellent "Composing Software" series of medium stories by Eric Elliott.

Edit: I see that each post in the series now has index, previous and next links. However, they don't follow a linear flow through all the articles with some pointing back to previous posts effectively locking you in a loop.

Regular Colors

Value	Color
\e[0;30m	Black
\e[0;31m	Red
\e[0;32m	Green
\e[0;33m	Yellow
\e[0;34m	Blue
\e[0;35m	Purple

	; THIS IS A Fennel SOURCE FILE (.fnl) !NOT! clojure!

	; you need to use luajit to run this, after using fennel --compile
	; install lapis and turbo from luarocks

	(local turbo (require "turbo"))
	(local render_html (. (assert (require "lapis.html")) :render_html))

	(fn render [parent expr]
	(parent:add_header "Content-Type" "text/html")

	From http://unix.stackexchange.com/questions/33381/getting-information-about-a-process-memory-usage-from-proc-pid-smaps

	For a given process in /proc/<pid>/smaps, for a given mapping entry what are:

	Shared_Clean
	Shared_Dirty
	Private_Clean
	Private_Dirty

	(ns pubsub-with-callbacks
	"Adapted from Timothy Baldridge's 2013 core.async examples:
	* https://raw.githubusercontent.com/halgari/clojure-conj-2013-core.async-examples/master/src/clojure_conj_talk/core.clj"
	(:require [clojure.core.async :as async]))

	(def pub-channel (async/chan 1))
	(def publisher (async/pub pub-channel :tag))
	(def print-channel (async/chan 1))

	(defn run-print-channel

	# Count total EBS based storage in AWS
	aws ec2 describe-volumes \| jq "[.Volumes[].Size] \| add"
	# Count total EBS storage with a tag filter
	aws ec2 describe-volumes --filters "Name=tag:Name,Values=CloudEndure Volume qjenc" \| jq "[.Volumes[].Size] \| add"
	# Describe instances concisely
	aws ec2 describe-instances \| jq '[.Reservations \| .[] \| .Instances \| .[] \| {InstanceId: .InstanceId, State: .State, SubnetId: .SubnetId, VpcId: .VpcId, Name: (.Tags[]\|select(.Key=="Name")\|.Value)}]'
	# Wait until $instance_id is running and then immediately stop it again
	aws ec2 wait instance-running --instance-id $instance_id && aws ec2 stop-instances --instance-id $instance_id

	# Get 10th instance in the account