module Enumerable

Similar to Enumerable#map, but builds a hash of the results using the original value as the key.

['john', 'paul', 'george', 'ringo'].map_h { |name| name.length }
# => {'john' => 4, 'paul' => 4, 'george' => 6, 'ringo' => 5}

# File lib/map_h.rb, line 7
def map_h
  {}.tap do |result|
    each do |key|
      result[key] = yield key
    end
  end
end