The SRFI has

     (mapping-map (proc (key value)
                (values (symbol->string key) value))
              (make-default-comparator)
              (mapping (make-default-comparator) 'foo 1 'bar 2 'baz 3))
     ; ⇒ (mapping (make-default-comparator) "foo" 1 "bar" 2 "baz" 3)

which is not indented correctly, and uses an unknown identifier `proc`.
It should be

     (mapping-map (lambda (key value)
                    (values (symbol->string key) value))
                  (make-default-comparator)
                  (mapping (make-default-comparator) 'foo 1 'bar 2 'baz 3))
     ; ⇒ (mapping (make-default-comparator) "foo" 1 "bar" 2 "baz" 3)

-- Peter McGoron