On Thu, Aug 13, 2009 at 4:59 PM, Daniel Lyons <fus...@storytotell.org>wrote:
>
> On Aug 13, 2009, at 2:30 PM, Brian Hurt wrote:
>
> I'm just wondering what people's response would be to allow user-generated
> reader macros. I'm not sure, but I think the only change to the clojure
> core that would be necessary in order to do this would be that in
> clojure/src/jvm/clojure/lang, LispReader.dispatchMacros would have to be
> made public. This would allow user code to update this array and add new
> macro functions.
>
> Now, I can certainly see a lot of potiential downsides to this. Redefining
> what #{} or #() means is just the start. But it'd make it a lot easier to
> do things with DSLs.
>
> So, what are people's thoughts?
>
>
> Trying to use them in Common Lisp has frustrated the crap out of me. The
> only library I know of that promulgates them seriously is CL-SQL and the
> gymnastics you have to do to install the reader macros are frustrating.
> Another library I tried to use I couldn't get to work at all (units, I
> think).
>
> In general I don't think they're worth the trouble. Reducing code
> compatibility is also a problem. Perhaps with namespaces there could be a
> better way to do it than CL does but I'm very wary of them. I don't think
> Scheme lets you have them at all.
>
>
Reading the responses to this thread, and thinking about things, I've come
around to this point of view.
What I wanted was the ability to read Clojure data structures from a file or
from stdin in a way that I could extend- for long, involved reasons I need
to specify byte arrays (as created by make-array Byte/TYPE) as fundamental
data structures, and was thinking I could just use the standard clojure
reader plus a new macro to do the byte arrays.
Except for two things- first of all, I don't want to use the standard
clojure reader in the first place, as I want to disallow things like lambda
closures. And second of all, the cost of allowing readers and rewriting the
syntax of the language as it's parsed, is huge. I'd be imposing a huge and
lasting cost on all clojure developers to save me a small cost right now.
And I don't think even plugging them into namespaces (which I don't see how
to do) would help all that much.
In any case, thanks everyone.
Brian
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