havenwood

require 'stringio'

def capture
  old_stdout, $stdout = $stdout, StringIO.new
  fake_stdout = $stdout
  yield
  $stdout = old_stdout
  fake_stdout.string
end

havenwood

module Mushroom
  @color = :blue

  def self.color
    @color
  end

  def self.color=(this_color)
    @color = this_color
  end

havenwood

class Integer
  def collatz_chain_size
    n = self
    chain = []
    until n == 1
      chain << n
      n.even? ? n /= 2 : n = n * 3 + 1
    end
    [chain.size, chain.first]
  end

havenwood

# http://users.minet.uni-jena.de/~dittrich//p/Dit2005upp.pdf
# https://github.com/videlalvaro/erlang-prime-sieve

require 'mathn'

module ChemicalPrime
  def self.take n
    sequence(n).map { |n| n * 2 + 1 }.unshift 2
  end

havenwood

def blink string, duration: 4, interval: 0.5
  start = Time.now
  while Time.now < start + duration
    print string
    sleep interval
    [?\r, ?\s, ?\r].each { |char| print char * string.size }
    sleep interval
  end
end

havenwood

module ArityRange
  def arity_range
    args = parameters.map &:first

    req = args.count :req
    opt = args.include?(:rest) ? Float::INFINITY : args.count(:opt)

    keyreq = args.count :keyreq
    keyopt = args.include?(:keyrest) ? Float::INFINITY : args.count(:key)

havenwood

module Enumerable
  def peek_at index
    value, _ = each_with_index.select { |_, i| index == i }.first
    value
  end
end

havenwood

module Iterator
  def self.new element, increment = 1
    Enumerator.new do |iteration|
      loop do
        iteration << element
        increment.abs.times do
          element = if increment >= 0
            element.next if element.respond_to? :next
          else
            if element.respond_to? :pred

havenwood

class Bdays
  attr_reader :birthdates

  def initialize n
    @birthdates = Array.new(n) { [*0..365].sample }.map do |s|
      birthday = Time.new(0) + s * 60 * 60 * 24
      [birthday.month, birthday.day]
    end

    shared_birthdates

havenwood

module ArrayIteration
  def next
    @index ||= 0
    raise StopIteration, 'iteration reached an end' if @index.next > size
    @index += 1
    self[@index.pred]
  end

  def pred
    @index ||= 0