arrow in ruby?

gistfile1.txt

c = ->(arr, *fs){ 
  arr.map{ |v| f = fs.empty? ? ->n{n} : fs.shift; Array(v).map(&f) }
} 


p c.([[1,2],[3,4]], ->n{n+1}, ->n{n+1})   #=> [[2, 3], [4, 5]]
p c.([[1,2],[3,4]], ->n{n+1})             #=> [[2, 3], [3, 4]]
p c.([[1,2],[3,4]])                       #=> [[1, 2], [3, 4]]

p c.([1,2], ->n{n+1}, ->n{n+1})           #=> [[2], [3]]
p c.([1,2], ->n{n+1})                     #=> [[2], [2]]
p c.([1,2])                               #=> [[1], [2]]