Zum Spaß mit TikZ `graphdrawing`.
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{graphs,graphdrawing}
\usegdlibrary{trees}
\begin{document}
\begin{tikzpicture}
\graph [trie,tree [fresh nodes,tree layout] {
"@" -> {
"@" -> {
"$\lambda$" -> {
"x", "$\mathrm{case_{List}}$" -> {
"x", "2", "3"
}
},
"Cons" -> {
"$\lambda$" -> {
/"z", /"z"
"z", "z"
},
"Nil"
}
},
"True"
}
};
\end{tikzpicture}
\end{document}
> ![alt text][1]
[1]: http://texwelt.de/wissen/upfiles/r_53.pnghttp://texwelt.de/wissen/upfiles/r_54.png