Re: string-set! examples in r5rs.html

[szgyg <szgyg@ludens.elte.hu>]

Ludovic Courtes writes:
> "Bill Schottstaedt" writes:
> 
>> according to r5rs.html, these should signal an error, I believe:
>>
>> guile> (string-set! (symbol->string 'immutable)
>>              0
>>              #\?)
>> guile> (define (g) "***")
>> guile> (string-set! (g) 0 #\?)
>> guile> (g)
>> "?**"

Not in R5RS. [1] But R6RS requires reporting. [2]

> The attached patches against 1.8.x fix this.
> 
> Neil: OK to apply?

No, (read) should return mutable string.

"literal constants and the strings returned by symbol->string are 
immutable objects, while all objects created by the other procedures 
listed in this report are mutable." [3]

So scm_read_string() should behave differently when reads program and data.

-------
#;> (string-set! (read) 2 #\X)
"12345"

Backtrace:
In current input:
    1: 0* [string-set! "12345" 2 #\X]

<unnamed port>:1:1: In procedure string-set! in expression (string-set! 
(read) 2 ...):
<unnamed port>:1:1: string is read-only: "12345"
ABORT: (misc-error)
-------

szgyg

[1] 
http://www.schemers.org/Documents/Standards/R5RS/HTML/r5rs-Z-H-4.html#%_sec_1.3.2
[2]
http://www.r6rs.org/final/html/r6rs/r6rs-Z-H-8.html#node_idx_248
[3] 
http://www.schemers.org/Documents/Standards/R5RS/HTML/r5rs-Z-H-6.html#%_idx_76