Re: [Chicken-users] fixnum-specific math operators patch

[Kon Lovett]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Sep 1, 2006, at 9:42 AM, Will M Farr wrote:

> Kon (and others),
>
> On Sep 1, 2006, at 10:59 AM, Kon Lovett wrote:
>
> > But Felix's point about 'ensure' should help w/ syntax forms that  
> > have domain & range restrictions.
>
> Yeah---that would be The Right Way (TM).  (And it allows for more  
> situation-adapted tests.)
>
> By the way (maybe felix can answer this), if I define a structure with
>
> (define-record foo bar baz)
>
> does it define the accessors and setters as
>
> (define (foo-bar f)
>   (ensure foo? f)
>   (block-ref f 0))

Sort of. Doesn't use 'ensure'. The type-check is always performed,  
but inline 'C'.

You can see what it makes in csi:

#;49> ,x (define-record a b c)
(begin
  (define make-a (lambda (b c) (##sys#make-structure 'a b c)))
  (define a? (lambda (x) (##sys#structure? x 'a)))
  (begin
    (define a-b-set!
      (lambda (x val) (##sys#check-structure x 'a) (##sys#block-set!  
x 1 val)))
    (define a-b
      (lambda (x) (##sys#check-structure x 'a) (##sys#block-ref x 1))))
  (begin
    (define a-c-set!
      (lambda (x val) (##sys#check-structure x 'a) (##sys#block-set!  
x 2 val)))
    (define a-c
      (lambda (x) (##sys#check-structure x 'a) (##sys#block-ref x  
2)))))

The 'misc-extn' egg has versions of SRFI-9 'define-record-type' which  
DO NOT perform
these type checks.

> ...
>
> I'm curious because I've read in other places (one of Manuel  
> Serrano's papers on type inference) that type checks can take up a  
> large fraction of the runtime, and it would be nice to eliminate as  
> many as possible in (unsafe) code.
>
> Will

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.3 (Darwin)

iEYEARECAAYFAkT4dQUACgkQJJNoeGe+5O6JXACggTG3a/xQmpcFVKIpnAg22JOS
uNkAn3Nhm1Qyo4DFqfJJMWREx+Nnj70R
=/LjY
-----END PGP SIGNATURE-----