gistfile1.rb

def scream(s)
  s.upcase
end

array = %w[i scream u scream we all scream for icecream]

## "On" the object
array.map(&:upcase)
# => ["I", "SCREAM", "U", "SCREAM", "WE", "ALL", "SCREAM", "FOR", "ICECREAM"]
array.map { |c| c.method(:upcase).call }
# => ["I", "SCREAM", "U", "SCREAM", "WE", "ALL", "SCREAM", "FOR", "ICECREAM"]

## Passes the object
array.map(&method(:scream))
# => ["I", "SCREAM", "U", "SCREAM", "WE", "ALL", "SCREAM", "FOR", "ICECREAM"]
array.map { |c| method(:scream).call(c) }
# => ["I", "SCREAM", "U", "SCREAM", "WE", "ALL", "SCREAM", "FOR", "ICECREAM"]