haskelldex.rb

#!/usr/bin/env ruby

require 'nokogiri'
require 'open-uri'

Doc = Nokogiri::HTML(open  "http://www.reddit.com/r/programming")

Entries = Doc.search("//div[@class='entry unvoted']")
  .map{ |e| e.at_xpath(".//a[@class='comments may-blank']")}
  .compact.map{|e| e.attributes['href'].value}
  .map{|e| Nokogiri::HTML(open e)}

def get_comments page
  xpath = "//div[@class='usertext-body may-blank-within']"
  # First element is always the subreddit description
  page.search(xpath).drop(1).map(&:text)
end

def count_haskells str
  str.split(/[^a-zA-Z]/).delete_if{|w| not w.casecmp("haskell").zero?}.length
end

def generate_report
  title_to_comments = Hash[Entries.map{|e| [e.title, get_comments(e)]}]
  
  title_to_haskells = Hash[title_to_comments.map do |k, v|
    hs = v.map{|comment| count_haskells comment}.inject(0, :+)
    [k, hs]
  end]

  total_comments = title_to_comments.values.map(&:length).inject(0, :+)
  total_haskells = title_to_haskells.values.inject(0, :+)

  puts "Comments: #{total_comments}"
  puts "Haskell mentions: #{total_haskells}"

  title_to_haskells.each do |title, hs|
    puts "#{title.chomp " : programming"}"
    puts "\t #{hs} haskell mentions"
  end
end

generate_report