{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 13,
   "id": "0f99fcb7-762f-447c-833d-f0e61b01cd3c",
   "metadata": {},
   "outputs": [],
   "source": [
    "fibs = 0 : 1 : zipWith (+) fibs (tail fibs)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "21cd7022-93ad-44e4-af07-695f2831ca47",
   "metadata": {},
   "source": [
    "it looks like the following"
   ]
  },
  {
   "cell_type": "raw",
   "id": "202121f5-b7d3-4a23-b29b-d0ad679cc5d2",
   "metadata": {},
   "source": [
    "0,1,1,2,3,5,8,13,21,34,55,89,144,233,377,610,987,1597,2584,4181,6765"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "e49c7c8c-8f40-4429-91c7-6f8ffd6ec261",
   "metadata": {},
   "source": [
    "get first item of each iteration and then drop 3 items from the beginning"
   ]
  },
  {
   "cell_type": "raw",
   "id": "b92a154b-99ad-4558-aeb1-635a4ad04570",
   "metadata": {},
   "source": [
    "0,2,8,34,144,610,2584"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "id": "9265e55e-64e6-4aff-a541-5896a032f66b",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "4613732"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "sum . takeWhile (<= 4000000) . map head . iterate (drop 3) $ fibs"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Haskell - haskell",
   "language": "haskell",
   "name": "ihaskell_haskell"
  },
  "language_info": {
   "codemirror_mode": "ihaskell",
   "file_extension": ".hs",
   "mimetype": "text/x-haskell",
   "name": "haskell",
   "pygments_lexer": "Haskell",
   "version": "9.0.2"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 5
}