🚀 go-pugleaf

In article <id.HHXO.DK9@ferranti.com> peter@ferranti.com (Peter da Silva) writes:
|No, because one supports the operation "extract X co-ordinate" and the
|other supports the operation "extract distance from origin". You can
|convert one to the other, and this might be a transparent operation
|(apart from considerations such as execution speed), but they are not
|the same type.

If it's transparent then I can't accept this explanation. But I don't
have a better one to offer; I just don't know how to think about this
case yet.

[string comparison uses numeric char order]
|Right, so you have a non-portable (that is, dependent on undefined
|behaviour) routine. In general you want to avoid this, so you hide
|this sort of code behind a subroutine interface. At least if you're
|smart you do.

But the *compiler* is justified in doing it, as is the library writer
(assuming that se knows what the character code is). I stressed the
word LEGITIMATE. The caller doesn't know, the routine does, by hypothesis.

|C is, by the way, not a good language for illustrating types because
|issues of type, machine type, storage class, and even scope are all
|muddied (for example, the same keyword is used to define static storage
|class and file scope). All you hot compiler hackers, come out with some
|good compilers for your language I can cheaply bootstrap and I'll dump
|C like a hot potato.

Workin' on it. But C is a good medium for discussing *implementations*
even if it's a lousy source language, precisely because the grunge shows.

[high tech data selection]
|Tough to do in C. Impossible to do portably. But sounds like a good way
|to do things in a higher level language. In C you would have to create
|a set of accessor macros that did appropriate tests and coercions, and
|fix the implementation up for each new platform (for example, on the 286
|it's very easy for a string to compare numerically less than 0).

Seriously trying to meet your challenge, you understand. I don't want
to have to write Mythos in C....

Portability isn't a problem either, unless your code generator, God
forbid, is hand-coded....
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stephen p spackman         Center for Information and Language Studies
stephen@estragon.uchicago.edu                    University of Chicago
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