Ruby in Haskell style

gistfile1.rb

# :: [event] -> [month,int]
def avg_lines_per_commit_by_month events
  cls_by_month = lines_added_per_commit(events).group_by {|date,_| month_from_date(date) }
  cls_by_month.map {|_,cls| cls.map {|cl| cl[1]}.mean }.flatten
end

# :: [event] -> Float
def percent_reduction method_events
  non_deleted = method_events.select {|e| e.status != :deleted }
  return 0.0 if non_deleted.count == 0
  num_reductions = non_deleted.each_cons(2) \
                              .map {|before, after| after.method_length < before.method_length } \
                              .count(true)
  num_reductions / non_deleted.count.to_f
end

# :: [event] -> [FixNum]
def refactoring_reduction_profile events
  events.group_by(&:method_name) \
        .map {|_,e| percent_reduction(e) } \
        .freq_by {|e| (e * 100 / 10).to_i  }
end