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6.4.19 SRFI-55 - Requiring Features

SRFI-55 provides 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.

— library syntax: require-extension clause...

Require each of the given clause features, 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.