Re: Srfi-159/166 - monadic formatting for guile

[Mark H Weaver <mhw@netris.org>]

Hi Linus,

Linus Björnstam <linus.internet@fastmail.se> writes:

> I just ported the reference implementation of SRFI-159/166 (166 being
> the successor of 159) from the reference implementation in chibi
> scheme. The srfi document is here:
> https://srfi.schemers.org/srfi-166/srfi-166.html
>
> SRFI-166 is like (ice-9 format) on steroids, drenched in molasses. It
> can do a lot more than (ice-9 format), but about 3x slower. I haven't
> started trying to make it fast just yet, but there are some low
> hanging fruit (like speeding up simple cases). I will wait with
> optimization until the srfi is finalized (and also maybe hear with
> Alex what he has in mind before trying to half-ass it myself).
>
> Anyway, the repo is here: https://bitbucket.org/bjoli/guile-srfi-159
> . I haven't ported the tests, but playing with it in guile and chibi
> scheme produces the same result. Tests are up, but I'm travelling
> without computer the next week, so there is no time.

I would be in favor of integrating this into Guile at some point,
although first I would like to make a careful review of the
implementation to make sure that it integrates well with Guile's related
mechanisms, e.g. custom record printers, printer options, and print
states, and that it supports all Guile data types.  In particular, I
remember finding it difficult to properly implement cycle detection
while supporting Guile's existing mechanisms.  I'm not sure it can be
done without modifying Guile's built-in printer.

I'll also want to take a close look at the numeric formatter, to make
sure that it achieves the same properties as our built-in printer,
e.g. that it prints inexacts with the minimal number of digits required
to ensure that the same number will be read back in (unless specifically
asked to limit the precision).

Anyway, thanks very much for sharing this!

    Regards,
      Mark