Since `return-from', used in conjunction with a `block' seems like nothing more than the lexical version of `throw', why does `return-from' take an &optional result-form, whereas `throw' requires its second argument (result-form)? It's a small detail, but I like to understand inconsistencies in the language, it this is one. I think the 2nd arg in `throw' should be optional.
David Bakhash <ca...@acs.bu.edu> writes: > Since `return-from', used in conjunction with a `block' seems like nothing > more than the lexical version of `throw', why does `return-from' take an > &optional result-form, whereas `throw' requires its second argument > (result-form)? It's a small detail, but I like to understand inconsistencies > in the language, it this is one. I think the 2nd arg in `throw' should be > optional.
History. It's a reasonable request that THROW should do likewise. But you should understand that THROW and BLOCK were not really originally understood to be so related and have each followed separate migration paths over a long period of time in order to get, as they are now, close enough to similar that you can see this.
It used to be that there was also a set of functions called ERRSET and ERR which were not substantially more than CATCH and THROW without ERR passing a value back. It took a while to realize that ERR and THROW were really redundant and to get them out. We got rid of ERR, which was good because it was kind of a mess, but we go rid of the 0-arg version of THROW in the process, which was probably bad.
All other things being equal, I'd advocate fixing this. But the expense of changing the standard is so high that likely the changes you'll see in the future will ber layerings, not corrections. Still, we'll see. That's just a guess on my part, not anyone's policy statement.
* Kent M Pitman <pit...@world.std.com> | All other things being equal, I'd advocate fixing this. But the expense | of changing the standard is so high that likely the changes you'll see in | the future will ber layerings, not corrections. Still, we'll see. | That's just a guess on my part, not anyone's policy statement.
hm? how would making an argument optional be expensive? it seems like it's a trivial thing to do, while, say, adding a required argument would be expensive. perhaps I'm misled by the work required to make it work that way in a conforming Common Lisp system:
I agree that this is not a big change, because it won't (AFAIK) break old code, and it won't change the behavior of Lisp, yet it will make it more consistent. Anyway, if one wanted to "request" such a change, who would he/she contact? Is there a place that you're supposed to write to people suggesting these changes, etc?
David Bakhash <ca...@acs.bu.edu> writes: > I agree that this is not a big change, because it won't (AFAIK) break old > code, and it won't change the behavior of Lisp, yet it will make it more > consistent. Anyway, if one wanted to "request" such a change, who would > he/she contact? Is there a place that you're supposed to write to people > suggesting these changes, etc?
You can pay your $600 in dues and become part of the current NCITS/J13 standardization process for the next revision of the ANSI Common Lisp standard, if the deadline for membership has not passed yet. You can contact s...@franz.com for details about joining and find out if it isn't too late, and you can subscribe to X3...@ai.sri.com, though it has been pretty quiet as discussion goes on now without public view by paying members only.
> You can pay your $600 in dues and become part of the current NCITS/J13 > standardization process for the next revision of the ANSI Common Lisp > standard, if the deadline for membership has not passed yet. You can > contact s...@franz.com for details about joining and find out if it > isn't too late, and you can subscribe to X3...@ai.sri.com, though it > has been pretty quiet as discussion goes on now without public view by > paying members only.
That last bit isn't correct: there is no discussion currently going on that is available to J13 people only (or if there is it is accidentally only reaching a subset!). There was an (informal) proposal that something like that should happen but nothing was actually done.
Another correction: there is no deadline for membership, although it runs by calendar year so if you join now you are paying $600 for 6 months.
However a large proportion of the J13 members probably read this newsgroup, so I should think that good ideas that appear here are at least being noticed.
