On Tue, Nov 26, 2013 at 12:34 PM, Michael Montague <xxxxxx@gmail.com> wrote:

Why can the procedure 'regexp' be called with an already compiled <re> which is just returned?

Why is the procedure 'valid-sre?' necessary? You could just call 'regexp' and use 'guard' to check for any errors.

Indeed, in fact `valid-sre?' could be defined as:

(define (valid-sre? x)

(guard (else (exn #f)) (regexp x)))

Whether you want to test in advance or catch errors

after the fact is a matter of personal style.

Alex