Pascal exercises

pascal.hs

pascal :: Int -> [[Int]]
pascal n = take n $ snd (foldl go ([], []) [0 .. n])
  where
    go :: ([Int], [[Int]]) -> Int -> ([Int], [[Int]])
    go ([], []) _ = ([1,1], [[1], [1,1]])
    go (lst, xs) _ = let newLst = sub lst False in (newLst, xs ++ [newLst])
    sub :: [Int] -> Bool -> [Int]
    sub (first : second : rest) False = 1 : first + second : sub (second : rest) True
    sub (first : second : rest) True = first + second : sub (second : rest) True
    sub [x] t = [1]
    sub [] t = []

pascal.js

function makeRow(oldRow)  {
  let oldN = null
  let newRow = []

  for (const n of oldRow) {
    if (oldN == null) {
      newRow.push(1)
      oldN = 1
    } else {
      newRow.push(oldN + n)
      oldN = n
    }
  }

  newRow.push(1)

  return newRow
}

function pascal(n) {
  let oldRow = null
  let rows = []
  for (let i = 0; i < n; i++) {
    console.log(oldRow, 'oldRow')
    if (oldRow == null) {
      rows = [[1]]
    } else {
      const newRow = makeRow(oldRow)
      rows.push(newRow)
    }
    oldRow = rows[i]
  }

  return rows
}

function main() {
  console.log(pascal(1))
  console.log(pascal(2))
  console.log(pascal(3))
  console.log(pascal(5))
  console.log(pascal(10))
}

main()