Re: [Chicken-users] symbol->string

[Thomas Chust]

On Mon, 23 Oct 2006, address@hidden wrote:

> [...] I looked at the definition of symbol->string and found out that it 
> is not a constant operation (like returning some pointer) but constructs 
> a string. Does anyone have a more efficient comparison of symbols 
> implemented? [...]

Hello,

as far as I know, symbols with identical names are always pointer equal in 
CHICKEN unless one of them has been created using gensym, so if you just 
need equality comparisons, eq? will be the fastest option.

If you want alphabetic ordering, you should avoid symbol->string, because 
it copies the name of the symbol to a new string -- this is necessary as 
Scheme's strings are mutable objects! I would suggest accessing the name 
slot of the symbol directly and defining

   (define (symbol-compare a b)
     (##sys#check-symbol a 'symbol-compare)
     (##sys#check-symbol b 'symbol-compare)
     (string-compare (##sys#slot a 1) (##sys#slot b 1)))

I hope that helps,
Thomas