Code for blog post: http://ruby.zigzo.com/2015/10/10/playing-with-crystal-lang/

goodtimes.cr

require "http/client"

class Word
  def initialize(word)
    raise ArgumentError.new "Not a single word" if word.split(" ").size > 1
    @word = word
  end

  def wiki_title
    wiki_page = WikipediaPage.new(@word)
    wiki_page.title
  end
end

class WikipediaPage
  def initialize(string)
    @string = string
  end

  def page
    @page ||= fetch
  end

  def title
    wikipedia_title_matcher = /<title[^>]*>(.*?) - Wikipedia, the free encyclopedia<\/title>/
    page.match(wikipedia_title_matcher) { |md| md[1] }
  end

  private def fetch
    url = "https://en.wikipedia.org/wiki/#{@string.capitalize}"
    response = HTTP::Client.get(url)
    response.body.lines.to_s
  end
end


##############
# RUNNER     #
##############

# Happy path
word = Word.new "tomato"
puts word.wiki_title

# Sad path
two_words = Word.new "so sorry"

##############
# OUTPUT     #
##############

# $ crystal run person.cr
# Tomato
# Not a single word (ArgumentError)
# [4502914194] *CallStack::unwind:Array(Pointer(Void)) +82
# [4502914097] *CallStack#initialize<CallStack>:Array(Pointer(Void)) +17
# [4502914056] *CallStack::new:CallStack +40
# [4502916609] *Exception@Exception#initialize<ArgumentError, String>:CallStack +33
# [4502916541] *ArgumentError#initialize<ArgumentError, String>:CallStack +29
# [4502916476] *ArgumentError::new<String>:ArgumentError +92
# [4502966288] *Word#initialize<Word, String>:String +64
# [4502966188] *Word::new<String>:Word +76
# [4502873457] __crystal_main +24097
# [4502881488] main +32