The document discusses the Ruby programming language and its features, including its friendly syntax, static type checking, modern standard library, ability to compile to fast native code, use of macros for metaprogramming, and status as a self-hosted language compiled and linked in Crystal. It encourages checking out Ruby and provides several links for more information.

1. Downtown Ruby Group May 2016Adrian Madrid
CRYSTAL LANG
friendly, static, modern, compiled

2. TL;DR VERY COOL
Adrian Madrid Downtown Ruby Group May 2016

3. FRIENDLY SYNTAX
def fibonacci(n)
return n if n <= 1
fibonacci(n - 1) + fibonacci(n - 2)
end
number = (ARGV[0]? || "40").to_i
puts "Calculating fibonacci for: #{number}"
puts fibonacci(number)
RUBY MOSTLY
Adrian Madrid Downtown Ruby Group May 2016

4. STATIC TYPE CHECKING
➤ All the benefits of static typing
➤ While figuring it all out on its own, mostly
DOH CHECKING
def foo(arg)
arg + 1
end
a = rand(2) == 0 ? 1 : nil
puts foo(a)
Adrian Madrid Downtown Ruby Group May 2016

5. MODERN STANDARD LIBRARY
➤ Spec (like RSpec)
➤ CSV, JSON, XML, YAML, Markdown
➤ HTTP Client & Server (WebSocket too)
➤ OAuth & OAuth2
➤ SecureRandom, Levenstein, HTML Builder, etc.
NEW STUFF
Adrian Madrid Downtown Ruby Group May 2016

6. COMPILES INTO FAST NATIVE CODE MICRO SECOND FAST
require “http/server”; require "http/server/handler"
host = "0.0.0.0"
port = 8080
handlers = [
HTTP::ErrorHandler.new,
HTTP::LogHandler.new,
HTTP::StaticFileHandler.new(“.")
]
server = HTTP::Server.new(host,port, handlers) do |context|
context.response.content_type = "text/plain"
context.response.print "Hello world!"
end
puts "Listening on http://0.0.0.0:8080"
server.listen
$ crystal build —release http_server.rb
$ ./http_server
Listening on http://0.0.0.0:8080
GET / - 200 (725µs)
GET / - 200 (82µs)
GET / - 200 (57µs)
Adrian Madrid Downtown Ruby Group May 2016

7. MACROS PRE-COMPILE METAPROGRAMMING
macro define_method(name, content)
def {{name}}
{{content}}
end
end
# This generates:
# def foo
# 1
# end
define_method foo, 1
foo #=> 1
Adrian Madrid Downtown Ruby Group May 2016

8. SELF HOSTED
➤ Compiled and linked
➤ You can cross-compile too
98.2% IN CRYSTAL
Adrian Madrid Downtown Ruby Group May 2016

9. LINKS
➤ Language - http://crystal-lang.org/
➤ API - http://crystal-lang.org/api/
➤ Code - https://github.com/manastech/crystal
➤ Docs - http://crystal-lang.org/docs/
➤ Libraries - http://awesome-crystal.com/
GO CHECK IT OUT
Adrian Madrid Downtown Ruby Group May 2016

10. http://crystal-lang.org/
Adrian Madrid Downtown Ruby Group May 2016