Re: XML: The good, the bad, and the ugly

From: Christopher Browne <cbbrowne_at_acm.org>
Date: 20 Oct 2004 00:34:16 GMT
Message-ID: <2tlq47F217j93U2_at_uni-berlin.de>


Martha Stewart called it a Good Thing when "Marshall Spight" <mspight_at_dnai.com> wrote:
> "Christopher Browne" <cbbrowne_at_acm.org> wrote in message news:2tj2geF1vkc12U1_at_uni-berlin.de...
>> Martha Stewart called it a Good Thing when "Marshall Spight" <mspight_at_dnai.com> wrote:
>> > But, as far as data management goes, they don't do so well; "Lisp program"
>> > as schema doesn't work as well as declarative schema-- Lisp is untyped.
>> > (But not as severely as XML.) Same issue with query language; it's better
>> > to write a declarative, content-addressing query than a procedure.
>>
>> Hum? Lisp is eminently strongly typed, whether we're talking about
>> the exceedingly sophisticated type tree of Common Lisp, or the
>> sparser arrangements in Scheme.
>
> But nothing is checked until runtime, so there are no type-based
> guarantees you can make about a well-formed LISP program. This
> isn't a good idea for data management, although there is a small but
> vocal minority that appears to think it's a good idea for writing
> programs. (I happen to think it's not a good idea for writing
> programs, either.)

Oddly enough, that, too, isn't actually the case.

It is quite common for Lisp compilers to do a fair bit of type checking at compile time.

The Python compiler (which was implemented _before_ other people adopted the name for a scripting language) does a quite remarkable amount of compile-time type checking for a language where "nothing is checked until runtime" and where "there are no type-based guarantees".

To wit:

  "If the compiler can prove at compile time that some portion of the   program cannot be executed without a type error, then it will give a   warning at compile time."

<http://www.math.sunysb.edu/~sorin/online-docs/cmucl/compiler.html#toc110>

-- 
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Received on Wed Oct 20 2004 - 02:34:16 CEST

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