Re: string is read-only

[Taylan Kammer]

On 03.08.2022 11:12, Damien Mattei wrote:
> GNU Guile 3.0.1
> Copyright (C) 1995-2020 Free Software Foundation, Inc.
> 
> Guile comes with ABSOLUTELY NO WARRANTY; for details type `,show w'.
> This program is free software, and you are welcome to redistribute it
> under certain conditions; type `,show c' for details.
> 
> Enter `,help' for help.
> scheme@(guile-user)> (define str2 "hello")
> scheme@(guile-user)> (string-set! str2 4 #\a)
> ice-9/boot-9.scm:1669:16: In procedure raise-exception:
> string is read-only: "hello"
> 
> Entering a new prompt.  Type `,bt' for a backtrace or `,q' to continue.
> scheme@(guile-user) [1]> ,q
> scheme@(guile-user)> (string? str2)
> #t
> 
> is it a bug in Guile ? :-O
> 
> i can only find reference to deprecated read-only string in old doc:
> https://www.gnu.org/software/guile/docs/docs-1.6/guile-ref/Read-Only-Strings.html#Read%20Only%20Strings
>  
> <https://www.gnu.org/software/guile/docs/docs-1.6/guile-ref/Read-Only-Strings.html#Read%20Only%20Strings>
> 
> Regards,
> 
> Damien

String literals are constants, and it's intentional.

I'm not sure if it's mentioned anywhere in the manual.

If you want to get a mutable string from a literal, you can use:

  (define str (string-copy "foobar"))

-- 
Taylan