\documentclass[tikz]{standalone}
\usepackage{stmaryrd}
\usetikzlibrary{arrows.meta,shapes.symbols,matrix,positioning}
\begin{document}
\begin{tikzpicture}[node distance=1em]
	\node (s1) {\verb#>>|.#};
	\node (d1) [left=of s1.north,yshift=-3em] {\verb#delay 500#};
	\node (s2) [right=of s1.south,xshift=-3em,yshift=-3em,fill=gray!15,label={[xshift=1em,label distance=-5pt]above:{\tiny interpreter}}] {\verb#writeD D3 st >>=. \x->#};
	\node (s3) [node distance=-.25em,below=of s2.south,fill=gray!15] {\verb#blink (Not x)#};
	\draw (s1.south) -- (d1.north);
	\draw (s1.south) -- ([xshift=-1em]s2.north);
\end{tikzpicture}
\end{document}
