\documentclass{article}
\usepackage{lisp-on-tex}
\lispinterp{%
  (\define \repl (\lambda ()
    (\begin
      (\stdprint (\eval (\read)))
      (\repl))))
}
\begin{document}
  \typeout{LISP on TeX interpretor mode}
  \lispinterp{(\repl)}
\end{document}