lazy iterator

lazyness.rb

arr = [1, 2, 3, 4, 5, 6, 7, 8]

[
  [1, 2, 3, 4, 5],
  [2, 3, 4, 5, 6],
  [3, 4, 5, 6, 7],
  [4, 5, 6, 7, 8],
  [5, 6, 7, 8],
  [6, 7, 8],
  [7, 8],
  [8]
]

def chunk_by(array, chunk_size)
  r = array.dup
  i = 0
  while i < r.length do
    i += yield(r[i , chunk_size])
  end
end

chunk_by(arr, 3) do |chunk|
  p chunk
  offset = 1
  if chunk == [3, 4, 5]
    puts 'Hola'
    offset += chunk.size
  end
  offset
end