Re: Guile: What's wrong with this?

[Bruce Korb <bruce.korb@gmail.com>]

Hi Mike,

Thank you for the explanation.  However:

On 01/03/12 07:03, Mike Gran wrote:
>> It worked until I "upgraded" to openSuSE 12.1.
>>
>>>   $ guile --version
>>>   guile (GNU Guile) 2.0.2
>>>   .....

>>>   (set! tmp-text (get "act-text"))
>>>          (set! TMP-text (string-upcase tmp-text))

 >>> ERROR: In procedure string-upcase:
>>> ERROR: string is read-only: ""
>>
>
> There does seem to be some strangeness w.r.t. read-only
> strings going on.
>
> On Guile 1.8.8 if you create a string this way, it is
> not read-only.
>
> guile>  (define y "hello")
> guile>  (string-set! y 0 #\x)
> guile>  y
> "xello"
>
> On Guile 2.0.3, if you create a string the same way, it
> is read-only for some reason.
>
> scheme@(guile-user)>  (define y "hello")
> scheme@(guile-user)>  (string-set! y 0 #\x)
> ERROR: In procedure string-set!:
> ERROR: string is read-only: "hello"
>
> %string-dump can be used to confirm this

There are a couple of issues:

1.  "string-upcase" should only read the string
     (as opposed to "string-upcase!", which rewrites it).
2.  it is completely, utterly wrong to mutilate the
     Guile library into such a contortion that it
     interprets this:
         (define y "hello")
     to be a request to create an immutable string anyway.
     It very, very plainly says, "make 'y' and fill it with
     the string "hello".  Making it read only is crazy.

Furthermore, I do not even have an obvious way to deal
with the problem, short of a massive rewrite.
I define variables this way all over the place.
rewriting the code to
    (define y (string-append "hell" "o"))
everywhere is stupid, laborious, time consuming for me,
and time consuming at execution time.

Guile 2.0.1, 2.0.2 and 2.0.3 need some rethinking.  Dang!!!!!