Determinant of a square diagonal matrix

How can I efficiently compute the determinant of a square diagonal matrix? In this case, the determinant is simply the product of each element in the diagonal. I can think of a couple options that might work:

  • I could store the diagonal of the matrix as a vector and apply a reduce operation to it (would I have to write my own reduce?). I think that one could implement a “poor man’s reduce” using map.
  • I could implement my own class, DiagonalMatrix, and add a determinant function to it.