On 22 Sep 2013, at 16:56, Scott McKay swmckay@gmail.com wrote:

On Sun, Sep 22, 2013 at 9:53 AM, Pascal Costanza pc@p-cos.net wrote: Hi,

It seems to me that ASSERT and CHECK-TYPE are not as convenient as they could be. In particular, ISLISP seems to have a better alternative in ASSURE.

ASSURE is easy to define:

(defmacro assure (type form) (let ((object (copy-symbol 'object))) `(let ((,object ,form)) (check-type ,object ,type) ,object)))

Yeah, this is really useful. One question -- is it also worth putting in (declare (type ,object ,type)) after the let-binding? Or does every competent compiler do the right thing once it's seen 'check-type'?

The type is only guaranteed after the check-type, so I don't think it's valid to put such a type declaration immediately after the let binding. After the check-type, it does not make much sense anymore, because immediately afterwards, the object is just returned.

Pascal

-- Pascal Costanza The views expressed in this email are my own, and not those of my employer.