3.5.1 Programs and libraries

A Scheme program consists of a top–level program together with a set of libraries, each of which defines a part of the program connected to the others through explicitly specified exports and imports.

• A library consists of a set of export and import specifications and a body, which consists of definitions, and expressions.
• A top–level program is similar to a library, but has no export specifications.

Chapters “Libraries” and “Top–level programs” describe the syntax and semantics of libraries and top–level programs, respectively. Chapter “Base library” describes a base library that defines many of the constructs traditionally associated with Scheme. A separate report describes the various standard libraries provided by a Scheme system.

The division between the base library and the other standard libraries is based on use, not on construction. In particular, some facilities that are typically implemented as “primitives” by a compiler or the run–time system rather than in terms of other standard procedures or syntactic forms are not part of the base library, but are defined in separate libraries. Examples include the fixnums and flonums libraries, the exceptions and conditions libraries, and the libraries for records.