memoed lambda triangle sum

const triangleMaxSum = (recur, triangle, row, column) => (row == undefined)
    ? recur(triangle, 0, 0)
    : (triangle.length - row == 1)
        // base case
        ? triangle[row][column]
        // recursive case
        : triangle[row][column] + Math.max(
            recur(triangle, row + 1, column),
            recur(triangle, row + 1, column + 1))

const memoize = (fn, cache, memo) =>
    ( cache = cache || []
    , memo = memo || ((...args) => (cache[args])
        ? cache[args]
        : ( cache[args] = fn(memo, ...args)
          , cache[args]))
    , memo)

// called as: memoize(triangleMaxSum)(triangleData)