1.3.1 Base and optional features
Every identifier defined in this report appears in one or more of
several libraries. Identifiers defined in the base library
are not marked specially in the body of the report. This library
includes the core syntax of Scheme and generally useful procedures that
manipulate data. For example, the variable abs is bound to a
procedure of one argument that computes the absolute value of a number,
and the variable + is bound to a procedure that computes sums.
The full list all the standard libraries and the identifiers they
export is given in Standard Libraries.
All implementations of Scheme:
- Must provide the base library and all the identifiers exported from it.
- May provide or omit the other libraries given in this report, but each
library must either be provided in its entirety, exporting no
additional identifiers, or else omitted altogether.
- May provide other libraries not described in this report.
- May also extend the function of any identifier in this report, provided
the extensions are not in conflict with the language reported here.
- Must support portable code by providing a mode of operation in which
the lexical syntax does not conflict with the lexical syntax described
in this report.