José Anchieta anchietajunior

Ruby: The future of frozen string literals

In programming languages, literals are textual representations of values in the source code. This is a syntactical concept.

Some examples:

7 # integer literal

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

-E: will describe the underlaying queries of the \ commands (cool for learning!)
-l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

Bin e padrões para validação de cartão de crédito.

Bandeira	Começa com	Máximo de número	Máximo de número cvc
Visa	4	13,16	3
Mastercard	5	16	3

start new:

tmux

start new with session name:

tmux new -s myname

Prereq:

apt-get install zsh
apt-get install git-core

Getting zsh to work in ubuntu is weird, since sh does not understand the source command. So, you do this to install zsh

	node: Platform built on V8 to build network applications
	git: Distributed revision control system
	wget: Internet file retriever
	yarn: JavaScript package manager
	python3: Interpreted, interactive, object-oriented programming language
	coreutils: GNU File, Shell, and Text utilities
	pkg-config: Manage compile and link flags for libraries
	chromedriver: Tool for automated testing of webapps across many browsers
	awscli: Official Amazon AWS command-line interface
	automake: Tool for generating GNU Standards-compliant Makefiles

	http://stackoverflow.com/questions/22667401/postgres-json-data-type-rails-query
	http://stackoverflow.com/questions/40702813/query-on-postgres-json-array-field-in-rails

	#payload: [{"kind"=>"person"}]
	Segment.where("payload @> ?", [{kind: "person"}].to_json)

	#data: {"interest"=>["music", "movies", "programming"]}
	Segment.where("data @> ?", {"interest": ["music", "movies", "programming"]}.to_json)
	Segment.where("data #>> '{interest, 1}' = 'movies' ")
	Segment.where("jsonb_array_length(data->'interest') > 1")