wanted: readable printing for specialized arrays

[Robert Brown]

When I evaluate the following with SBCL

  (defvar *f* (make-array 10 :element-type '(unsigned-byte 8)))
  (with-standard-io-syntax (print *f*))

a PRINT-NOT-READABLE condition is signaled. Other Common Lisp
implementations allow readable printing of specialized arrays:

CLISP outputs

  #A((|COMMON-LISP|::|UNSIGNED-BYTE| 8.) (10.) (0. 0. 0. 0. 0. 0. 0. 0. 0. 0.))

Lispworks outputs

  #.(COERCE #(252 140 140 245 0 0 0 0 123 86)'(SIMPLE-ARRAY (UNSIGNED-BYTE 8) (10)))

I would like something similar for SBCL. CLISP's extension of the #A
reader macro looks pretty reasonable. Are there any hidden issues
with implementing this array reading extension in SBCL as well?

bob

====================

paradicsom [23645] sbcl --version
SBCL 1.0.49.62-99a669b

paradicsom [23646] uname -a
Linux paradicsom.nyc.corp.google.com 2.6.32-gg508-generic #gg508-Ubuntu SMP
Tue May 24 05:09:12 PDT 2011 x86_64 GNU/Linux

[Robert Brown (robert-brown)]

Attached is a patch against SBCL 1.0.52 that implements readable printing
for specialized arrays.

Would someone be willing to review this change?

bob

[Robert Brown (robert-brown)]

Updated patch.

[Robert Brown (robert-brown)]

Updated patch for recent printing changes.

[Nikodemus Siivola (nikodemus)]

I've merged this to my pending tree.

https://github.com/nikodemus/SBCL/commit/630624faaf6287ebd117d8e2c3f89d6516f1c7ba

[Nikodemus Siivola (nikodemus)]

Nothing this here, so it won't get lost.

I think we should also add *print-portably*, defaulting to T.

When it is bound to NIL we could print base-strings as #"foo" and specialized arrays as #A(simple-array <dims> <etype> <contents>), similar to CMUCL (regardless of the value of *print-readably*.)

Then we could also add PRINT-UNPORTABLY restart.

[Nikodemus Siivola (nikodemus)]

commit 628c9c353690b012965ccd74d68e1b81e4a2a368
Author: Robert Brown <email address hidden>
Date: Fri Dec 2 17:07:20 2011 +0200

    printing specialized arrays readably

      When *READ-EVAL* is true, use #. based syntax to print them.

      lp#803665.