[Chicken-users] symbol->string

[F. Wittenberger]

Hi all,

my reading of R5RS allows   symbol->string to be implemented more
efficiently - though not as safe:

"""
procedure:  (symbol->string symbol) 

Returns the name of symbol as a string. ... It is an error to apply
mutation procedures like string-set! to strings returned by this
procedure.
"""

I'm reading: "it is ok to return some interned string, which, when
mutated will cause all sorts of harm to the Scheme system, but if the
implementer chooses to return a fresh copy each time and keep the Scheme
running, it's ok too".

In other words: the source shows: chicken goes the safe path here.
(In case of qualified symbols, it's worse: the string is copied twice
and one copy always discarded.)


But that might be costly!  I have a lots of cases, where the result of
string->symbol is used and, since I've been careful about the above
cited sentence from R5RS, none which mutate the resulting string.

Hence I tried.

In my case the following definition (in the lowest level module of my
app) gains me a factor of two in runtime!!

(global-set! 'symbol->string
 (lambda (s)
  (##sys#check-symbol s 'symbol->string)
  (##sys#symbol->string s)))

YMMV however.

Best regards

/Jörg