From: Simon Buchan (simon_at_[hidden])
Date: 2005-09-27 19:34:50
Jonathan Turkanis wrote:
> Simon Buchan wrote:
>>Jonathan Turkanis wrote:
>>>Note that I'm not criticising the standard (although it certainly
>>>has some problems with lack of precision). It would be nice to have
>>>a truly formal specification, but in the case of C++ it's probably
>>I do think it's possible
> I said 'realistic'
I should have /emphasised/ it, sorry.
>>(If it wasn't, we wouldn't be able to write
>>compilers for it!),
> That's like saying: Of course it must be possible to provide a formal semantics
> for English -- otherwise I'd never be able to understand the instructiosn that
> come with my coffee maker :-)
Can you? If so, English (or more precisely, the subset used in the
instructions) can be formally defined (in fact, you can find programs
that do). The problem with natural languages is that they have a symbol
table with trillions of entries, and that table is dynamicly generated
based on the situation the compiler (ie, you) is in.
>>but remember the standard has basicly grown out of
>>rewordings from the days of C (which did likewise back to B, etc...)
>>I think a formal, but human-readable, grammar, kind of like EBNF for
>>semantics, would be useful here.
> It would be very useful (except I'm not sure what you mean by "kind of like EBNF
> for semantics")
Think algebra for syntax. That's EBNF. I don't know of any generalised
definition of semantics (Turing machines don't count, 'cause they arn't
human-readable (even the definition of Turing machines arn't!), and
Lambda Calculus isn't general enough.) that would be useful, but feel
free to correct me.
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