block_examples.rb

### A SIMPLE EXAMPLE OF BLOCKS

numbers = [1, 2, 3, 4, 5]

# .each iterates through an array or hash and performs an anonymous function on it
numbers.each { |n| puts "The square of #{n} is #{n**2}" }
# note also the string interpolation with the #{} 
# note that numbers is unchanged
p numbers
puts "\n\n--------\n\n"

# another way of representing a block via do..end
numbers.each do |n| 
  puts n**2
end
p numbers
puts "\n\n--------\n\n"

# .map interates through the array, performs the anon function and returns the result to a new array
squares = numbers.map { |n| n**2 }
# original array unchanged
p numbers
# a new array with squared values
p squares
puts "\n\n--------\n\n"

# .select filters an array or hash and returns only those values for which the anon function returns true
evens = numbers.select { |n| n%2 == 0 }
p numbers  # original still unchanged
p evens
puts "\n\n--------\n\n"

# %w makes a special word array w/o quote marks and delimited by spaces
colors = %w[blue red orange green purple yellow]
p colors
p colors.sort

# here we are making a hash with some syntactic sugar
color_enum = {blue: 0, red: 2, orange: 4, green: 1, purple: 3, yellow: 5}
# this is how Ruby sees the array
p color_enum

# can sort_by any criterion specified in the block; in this case, by values
p color_enum.sort_by { |k,v| v }

# checking to see what's included; separating the hash into keys and values arrays
puts color_enum.keys.include? :blue
puts color_enum.values.include? 7