(let queenPuzzle (fun (rows columns)
  (if (<= rows 0)
    [[]]
    (addQueen (- rows 1) columns))))

(let addQueen (fun (newRow columns) {
  (mut newSolutions [])
  (let prev (queenPuzzle newRow columns))

  (mut i 0)
  (while (< i (len prev)) {
    (let solution (@ prev i))
    (mut newColumn 0)
    (while (< newColumn columns) {
      (if (not (hasConflict newRow newColumn solution)) (append! newSolutions (append solution newColumn)))
      (set newColumn (+ newColumn 1)) })

    (set i (+ i 1)) })

  newSolutions }))

(let hasConflict (fun (newRow newColumn solution) {
  (mut i 0)
  (mut conflict false)
  (while (and (< i newRow) (not conflict)) {
    (if (or (= (@ solution i) newColumn) (= (+ (@ solution i) i) (+ newColumn newRow)) (= (- (@ solution i) i) (- newColumn newRow)))
      (set conflict true))
    (set i (+ i 1)) })

  conflict }))

(print (queenPuzzle 4 4))