require-extension which is a portable
mechanism to load selected SRFI modules. This is implemented in the
Guile core, there’s no module needed to get SRFI-55 itself.
Require the features of clause1 clause2 … , throwing an error if any are unavailable.
A clause is of the form
(identifier arg...). The
only identifier currently supported is
srfi and the
arguments are SRFI numbers. For example to get SRFI-1 and SRFI-6,
(require-extension (srfi 1 6))
require-extension can only be used at the top-level.
A Guile-specific program can simply
use-modules to load SRFIs
not already in the core,
require-extension is for programs
designed to be portable to other Scheme implementations.