IntroductionEvery language comes with collections of programs that are reusable by
the programmer, called libraries. The quality and diversity of
these programs are often some of the criteria one uses to assess the ease
of use of a language. You could separate libraries into two categories:
those that offer types and functions that are often useful but could be
written in the language, and those that offer functionality that cannot
be defined in the language. The first group saves the programmer the
effort of redefining utilities such as stacks, lists, etc. The second
group extends the possible uses of the language by incorporating new
functionality into it.
The Objective CAML language distribution comes with many precompiled
libraries. For the curious reader, the uncompiled version of these
libraries comes packaged with the source code distribution for the language.
In Objective CAML, all the libraries are organized into modules that
are also compilation units. Each one contains declarations of globals
and types, exceptions and values that can be used in programs. In this
chapter we are not interested in how to create new modules; we just want
to use the existing ones. Chapter 14 will revisit the concepts
of the module and the compilation unit while describing the
module language of Objective CAML, including parameterized modules. Regarding
the creation of libraries that incorporate code that is not written in Objective CAML,
chapter 12 will describe how to integrate Objective CAML programs
with code written in C.
The Objective CAML distribution contains a preloaded library (the
Pervasives module), a collection of basic modules called the
standard library, and many other libraries adding functionality
to the language. Some of the libraries are briefly shown in this chapter
while others are described in later chapters.