Kind of a odd example just to use map/reduce where each works just fine: result = Hash.new(0) Dir['test?.txt'].each do |file| File.read(file).spl

Kind of a odd example just to use map/reduce where each works just fine: result = Hash.new(0) Dir['test?.txt'].each do |file| File.read(file).split(' ').each {|word| result[word.downcase.tr('.,\'', '')] += 1} end If you really needed map/reduce here you'd probably want to write it this way: Dir['test?.txt'].map do |file| Hash.new(0).tap {|result| File.read(file).split(' ').each {|word| result[word.downcase.tr('.,\'', '')] += 1}} end.reduce do |result, partial| result.merge(partial) {|k, v1, v2| v1 + v2} end