\chapter{Future additions to this library}
\label{chap-future}

\section{More algorithms on existing trees}

Since this library supplies concrete tree representations basic
algorithms on such trees, we will not include abstractions based on
binary trees such as binary search trees or red-black trees.  We
might, however, add operations for navigating trees, and for inserting
and deleting nodes, provided we find the right abstractions for these
operations.

We will also add more fundamental algorithms on binary trees, such as
turning an arbitrary tree into a \emph{skinny} tree, and turning a
skinny tree into a balanced tree.

\section{New types of trees}

Although we will not add abstractions on top of existing
representations and algorithms, we will, however, include completely
new tree representations, and in particular \emph{2-3 trees}
\cite{Aho:1974:DAC:578775} since they have a reputation for being hard
to implement.
