Challenge 2: Symbol#to_proc in Practice — Solution

words = ["Hello", "WORLD", "RuBy"]

# Shorthand
lowercased = words.map(&:downcase)
puts lowercased.inspect

# Full block, same result
lowercased_block = words.map { |word| word.downcase }
puts lowercased_block.inspect

=begin
Output:
["hello", "world", "ruby"]
["hello", "world", "ruby"]

Notes:
- &:downcase converts the :downcase symbol into a Proc (via Symbol#to_proc)
  and then expands that Proc into a block for .map, calling .downcase on
  each element in turn.
- words.map { |word| word.downcase } does the identical thing, spelled out
  the long way with an explicit block parameter.
- The shorthand is idiomatic Ruby specifically because the block only does
  one thing — call a single method with no arguments on each element. Once
  the block needs more logic than that, the full block form is the better
  (and often only workable) choice.
=end