KamilLelonek

[1] (pry) main: 0> outer = 1
=> 1

[2] (pry) main: 0> increment = -> value { outer + value }
=> #<Proc:0x007fb94c87e148@(pry):2 (lambda)>

[3] (pry) main: 0> increment[2]
=> 3
[4] (pry) main: 0> increment::(2)
=> 3

KamilLelonek

[1] (pry) main: 0> def factorial(number)
[1] (pry) main: 0*   return 1 if number <= 1
[1] (pry) main: 0*   number * factorial(number - 1)
[1] (pry) main: 0* end
=> :factorial

[2] (pry) main: 0> factorial(4)
=> 24

[3] (pry) main: 0> def factorial(number, accumulator = 1)

KamilLelonek

[1] (pry) main: 0> { key: :val }.fetch(:key, raise('Key does not exist'))
RuntimeError: Key does not exist

[2] (pry) main: 0> { key: :val }.fetch(:key) { raise('Key does not exist') }
=> :val

[3] (pry) main: 0> Array.new(3, rand(10))
=> [0, 0, 0]

[4] (pry) main: 0> Array.new(3) { rand(10) }

KamilLelonek

[1] (pry) main: 0> %w(ruby is awesome).map &:upcase
=> ["RUBY", "IS", "AWESOME"]

[2] (pry) main: 0> def shuffle_letters(word)
[2] (pry) main: 0*   word.split(//).shuffle.join
[2] (pry) main: 0* end
=> :shuffle_letters

[3] (pry) main: 0> %w(ruby is awesome).map &method(:shuffle_letters)
=> ["ubyr", "is", "emasewo"]

KamilLelonek

[1] (pry) main: 0> a = 1
=> 1

[2] (pry) main: 0> b = 2
=> 2

[3] (pry) main: 0> def add(a, b)
[3] (pry) main: 0*   a + b
[3] (pry) main: 0* end
=> :add

KamilLelonek

[1] (pry) main: 0> def print_and_dump(string)
[1] (pry) main: 0*   open('dump.txt', 'a') do |file|
[1] (pry) main: 0*     puts string
[1] (pry) main: 0*     file.puts string
[1] (pry) main: 0*   end
[1] (pry) main: 0* end
=> :print_and_dump

[2] (pry) main: 0> print_and_dump('test')
test

KamilLelonek

def divide(dividend, divisor)
  dividend / divisor
rescue ZeroDivisionError
  p $!.message
end

def average(*values)
  raise ArgumentError.new('No values given')            if     values.empty?
  raise ArgumentError.new('Not all values are numbers') unless values.all? { |value| value.is_a? Numeric }
  values.reduce(:+) / values.length

KamilLelonek

[1] (pry) main: 0> sum = -> (a, b) { a + b }
=> #<Proc:0x007fa9c176e950@(pry):59 (lambda)>

[2] (pry) main: 0> increment = -> c { sum.(1, c) }
=> #<Proc:0x007fa9c173c900@(pry):60 (lambda)>

[3] (pry) main: 0> increment[3]
=> 4

KamilLelonek

module A
  extend self

  def a
    puts 'a'
  end
end

A.a # => 'a'

KamilLelonek

module B
  module_function

  def b
    puts 'b'
  end
end

B.b # => 'b'