4.2.1 Standard Names

This section doesn’t apply to R7RS source or library files, since their environments are completely specified by import statements.

Other source files usually contain a line

(declare (usual-integrations))

near their beginning, which tells the compiler that free variables whose names are defined in system-global-environment will not be shadowed by other definitions when the program is loaded. If you redefine some global name in your code, for example car, cdr, and cons, you should indicate it in the declaration:

(declare (usual-integrations car cdr cons))

You can obtain an alphabetically-sorted list of the names that the usual-integrations declaration affects by evaluating the following expression:

(eval '(sort (append usual-integrations/constant-names
                     usual-integrations/expansion-names)
             (lambda (x y)
               (string<=? (symbol->string x)
                          (symbol->string y))))
      (->environment '(scode-optimizer)))