(function :FerrySquare floor [:Array<FerrySquare> n :SeatsChanged changed] floor)

(function :FerrySquare emptySeat [:Array<FerrySquare> n :SeatsChanged changed]
    // Empty seats with completely empty neighbors, fill up
    (cond
        ((= true (apply = (for neighbor n #{neighbor != fullSeat;}#)))
            (set changed.changed true)
            fullSeat)
        (true emptySeat)))

(function :FerrySquare fullSeat [:Array<FerrySquare> n :SeatsChanged changed]
    // Full seats with 4 or more full neighbors become empty
    (cond
        ((<= 4 (count n (lambda [neighbor] #{neighbor == fullSeat;}#)))
            (set changed.changed true)
            emptySeat)
        (true fullSeat)))

(function neighbors [x y :Array<Array<FerrySquare>> grid]
    (localVar &mut n [])
    (doFor xx (range (- x 1) (+ x 2))
        (doFor yy (range (- y 1) (+ y 2))
            (unless (and (= x xx) (= y yy))
                (when (and (<= 0 xx) (<= 0 yy) (> grid.length yy) (> .length (nth grid yy) xx))
                    (n.push (nth (nth grid yy) xx))))))
    n)

(prop &mut :Array<Array<FerrySquare>> state [])

(method simulate []
    (localVar changed (object changed false))
    (set state
        (for rowIdx (range state.length)
            (let [:Array<FerrySquare> row (nth state rowIdx)]
                (for seatIdx (range row.length) ((nth row seatIdx) (neighbors seatIdx rowIdx state) changed)))))
    changed.changed)

(method fullSimulate []
    (when (simulate) (fullSimulate)))

(method countFullSeats []
    (apply +
        (for :Array<FerrySquare> row state
            (apply +
                (for :FerrySquare seat row
                    (if #{seat == fullSeat;}# 1 0))))))

(defReaderMacro "L" [stream] `emptySeat)
(defReaderMacro "#" [stream] `fullSeat)
(defReaderMacro "." [stream] `floor)
(undefReaderMacro "...")

(defReaderMacro &start "" [stream]
    `(state.push ,(ReaderExp.ListExp (readExpArray stream "\n"))))