Re: Problem with type conflict style warning

On 5/15/24 8:11 AM, syll-dev wrote:
> Hello
>
> I don't understand this style warning...
>
> Here is the code (problem with test1 only) :
> "
> (ql:quickload :alexandria)
> (use-package :alexandria)
>
> (defvar *l* '(1 2 3))
>
> (defun test1 ()
>    (copy-sequence 'vector (reverse *l*)))
>
> (defun test2 ()
>    (copy-sequence 'vector *l*))
>
> (defun test3 ()
>    (copy-sequence 'vector '(1 2 3)))
>
> (defun test4 ()
>    (let ((l '(1 2 3)))
>      (copy-sequence 'vector l)))
> "
>
> And here is the result :
> "
> ; in: DEFUN TEST1
> ;     (COPY-SEQUENCE 'VECTOR (REVERSE *L*))
> ; --> BLOCK IF COERCE
> ; ==>
> ;   1
> ;
> ; caught STYLE-WARNING:
> ;   Derived type of SB-C::X is
> ;     (VALUES (OR LIST SB-KERNEL:EXTENDED-SEQUENCE) &OPTIONAL),
> ;   conflicting with its asserted type
> ;     VECTOR.
> ;   See also:
> ;     The SBCL Manual, Node "Handling of Types"
> "
>
> sbcl 2.4.1 and 2.4.4 (other versions not tested).
>
> I have the same problem with remove-if-not instead of reverse.
>
> Thank you
>
> syll
>
>
the function copy-sequence is in alexandria.


(defun copy-sequence (type sequence)
   "Returns a fresh sequence of TYPE, which has the same elements as
SEQUENCE."
   (if (typep sequence type)
       (copy-seq sequence)
       (coerce sequence type)))


Here are some easy ones.

;;;; coerce

(defparameter lst (list 1 2 3))

(defun list-to-vector (lst)
   (apply #'vector lst))

(defun list-to-vector-coerce (lst)
   (coerce lst 'vector))

(list-to-vector-coerce lst)
=> #(1 2 3)

(reverse #(1 2 3))
(reverse (list 1 2 3 4))


(remove-if-not #'oddp #(1 2 3 4 5))
(remove-if #'evenp (list 1 2 3 4 5))

=> (1 3 5)

I usually stay away from the external packages. it's a pain in the a$$ .

The problem as I see it. vectors look like #(1 2 3 4) lists look like (1 
2 3 4),

notice the #






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