\documentclass[border=5mm]{standalone}
\usepackage{luamplib}
\begin{document}
\mplibtextextlabel{enable}
\begin{mplibcode}
beginfig(1);
    draw (left--right) scaled 2in withcolor 2/3 red;
    for i=-4 upto 4:
        dotlabel.top("$" & decimal i & "$", (32i, 0));
    endfor
endfig;
\end{mplibcode}
\end{document}