Printing a matrix in Maxima, again

My adventure continues:

printMatrix(a) := block([as, body],
     as : matrixmap(lambda([x],
                      printf(false, "~a", x)), a),
    body: simplode(maplist(lambda([row],
                             simplode(row, " & ")),
                                         as),
              sconc(" ", "\\\\", newline)),
     sconc("\\left(\\begin{array}{",
                 simplode(makelist("r", i, 1,
                                    length(a[1]))), "}",
                 newline,
                 body,
                 newline,
                 "\\end{array}\\right)"))$

There's just got to be a function in Maxima somewhere that already does this. (There's also just got to be a function that creates a list based on repeating an element. makelist(x, i, 1, n) does the job though.)

(%i42) printMatrix(diag_matrix(1,2,3));
(%o42) \left(\begin{array}{rrr}
1 & 0 & 0 \\
0 & 2 & 0 \\
0 & 0 & 3
\end{array}\right)

Also in the spirit of duplicating functionality that's just gotta be out there: Escape HTML characters. I use this pretty often. Maybe I should make it spiffier.