[gambit-list] Readtables in Files

I was wondering if it is possible to change a readtable while loading a file. I have the file tt.scm with the following contents

(output-port-readtable-set!

(current-output-port)

(readtable-keywords-allowed?-set

(output-port-readtable (current-output-port))

#f))

(input-port-readtable-set!

(current-input-port)

(readtable-keywords-allowed?-set

(input-port-readtable (current-input-port))

#f))

(display (map keyword? '(foo :foo foo:)))

If the readtable had changed it would've produce #f #f #f when I had typed (load "tt.scm"). Rather, it displays #f #f #t.

So is it possible to change the readtable of the file currently being read so that display produces the correct output.