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Re: Fundamental operations on strings




On Wed, 13 Jul 2005, Shiro Kawai wrote:

>The current draft says:

>   Like in R5RS, a Scheme string is a fixed-length
>   array of Scheme characters.

> What R5RS says is "Strings are sequences of
> characters."  Although having make-string,
> string-ref and string-set! as primitives suggests
> R5RS authors had an array model in their mind, a
> string can be implemented differently.  If strings
> are meant to manipulate texts, as stated in this
> srfi, such alternative implementation can even be
> better than the simple "fixed-length mutable array
> of characters" view.

I strongly agree.  Using Unicode makes length-changing
mutations even more likely than before, and frequently
forces it in unexpected situations where the end-user
won't understand or expect it; implementors need to be
free to implement strings in a way that makes
length-changing mutations efficient.  Don't stick them
to a fixed-length mutable array.

In particular, don't spec something that outlaws "ropes";
they are much closer to being "the right thing."

			Bear