On 6/20/07, William D Clinger <will at ccs.neu.edu> wrote:
> Sam TH wrote:
> > Are any of these "truly useful" extensions implemented in a
> > currently-available Scheme system?
>
> Yes. Many existing systems provide customizable readers,
> and redefining [ and ] to do something useful is one of
> the more popular customizations. Jonathan's proposal is
> an attempt to preserve this legacy.
Customizable readers are a very different kettle of fish from the
non-hygenic introduction of the *square-bracket* identifier in a few
particular cases. Customizable readers can do very different things
from those done with your proposal (sharing read syntax, for example),
are implemented in a very different way, and require the programmer to
specify (in some fashion) the use of the customized reader in order
for them to be used.
I think customizable readers are an excellent idea, and perhaps should
be proposed for the Scheme Report. But maybe they should wait for
R7RS.
Finally, the R6RS has admirably refrained from specifying too many
proposals that had not previously been implemented, and that the
community has no experience with. Your and Jonathan's proposal would
add another instance of this.
--
sam th
samth at ccs.neu.edu
Received on Wed Jun 20 2007 - 11:16:15 UTC