\usetikzlibrary{arrows.meta,shapes.symbols,matrix,positioning}
\begin{document}
\begin{tikzpicture}[node distance=1em]
- \node (s2) {\verb#>>=.# $\lambda x\shortrightarrow$};
+ \node (s2) {\verb#>>=. \x->#};
\node (wd) [left=of s2.north,yshift=-3em] {\verb#writeD D3 st#};
\node (rec) [right=of s2.north,yshift=-3em,fill=gray!15,label={[xshift=1em,label distance=-5pt]above:{\tiny interpreter}}] {\verb#blink (Not x)#};
\draw (s2.south) -- (wd.north);