\chapter{Introduction}
\pagenumbering{arabic}%

\sysname{} is a library that supplies a collection of different kinds
of \emph{trees}.

\chapter{Introduction}
\pagenumbering{arabic}%

\section{Purpose}

\sysname{} is a library that supplies a collection of different kinds
of \emph{trees}.

\sysname{} differs from other libraries with trees, such as
\texttt{cl-containers} in that it has a \emph{stratified design}.
This design allows client code to intervene at all levels, from the
level of near-concrete representation of the trees, up to the most
abstract interface where the trees are used as dictionaries,
sequences, or some other abstract data types.

Also, the stratified design makes it possible for client code to use
the lower levels of abstraction of \sysname{} in order to create
completely new abstractions, not foreseen by this library.

The price to pay for this stratified design is, of course, that lower
abstraction levels are exposed to client code, and are therefore
limited in the way that they can evolve.  As a consequence, we have
tried to create these lower abstraction levels in a way that they are
unlikely to require radical modifications.

Expand on the purpose of Clump.
Expand on the purpose of Clump.
