[Maxima] Maxima from Lisp

[Nicolas Neuss]

Hello,

I would like to call Maxima from the underlying Lisp for communicating with
a user.  Therefore, I am interested in Lisp functions for writing data in
2d-format to a stream or string, and functions for evaluating a string
containing a mathematical expression.  E.g., something like
  (display2d (meval "x+x^2") stream)
should write
     2
    x  + x
to the stream.

Thank you for any help,
Nicolas