[M3devel] C-like syntax for Modula-3 [was Re: "target specific pragmas"?]

[Olaf Wagner]

I'd rather not go this way and change the complete syntax and
convert to and fro between the two. If we really want to do that,
I'd rather have it as something like a compatible extension (as far
as possible).

What about changing only the keywords from uppercase to lowercase
and using {} instead of BEGIN END? I'm not sure if that would
satisfy the C-adherents, and I'm also not sure if it would
introduce syntactic ambiguities, as {} are also used for sets.
I'd like to keep the changes to the syntactical structure minimal
(upper- and lowercase is only lexical matter after all). The abstract
syntax should be kept as it is.

If something like this would be possible, I'd vote for supporting
both syntaxes in one compiler and turn on the C-style by a comment
or automatically by recognizing the first word of a module. I'd not
support mixing of styles within one module.

Olaf

PS: I'm not really suggesting we do this now, I just wanted to comment
     on the possibility of doing something like this. Anyway it will
     depend on somebody who provides appropriate patches and updates
     the language specification etc.

Quoting Mika Nystrom <mika at async.caltech.edu>:

> Well I used to be mostly a C programmer but I long since weaned
> myself off that syntax :)
>
> Your point of the post- and pre-increment might be a bit difficult
> for C programmers to stomach, but... well it is probably hard to
> tell what programmers will hate and what they will love.
>
> Wouldn't a way to go about it be to take the Modula-3 BNF and modify
> the rules as needed?  Would you like to be able to convert back and
> forth (why not), e.g., using m3tk (m3pp?)?  You have to lower-case
> all the keywords, convert the braces appropriately (a bit tricky
> since Modula-3 has abandoned the Pascal/Algol FOR i := 0 TO 10 DO
> BEGIN END, so braces map only to the ENDs, not BEGINs (for the most
> part)).
>
> Type "attributes"(is that the right word?) are also an area where
> Modula-3 is significantly different from the C family.  In C, you
> write
>
> int *a, *b, c;
>
> we have
>
> REF INTEGER a, b;
> INTEGER c;
>
> And arrays?
>
> VAR arr : REF ARRAY OF ARRAY [FIRST(SomeEnum)..LAST(SomeEnum)] OF ARecord;
>
> ARecord *arr[][first(SomeEnum)..last(SomeEnum)];
>
> I prefer Algol syntax myself but I could definitely see that there
> might be people who would prefer a syntax mapped to C.  One might
> be able to sneak Modula-3 into places where it wouldn't otherwise
> be used...
>
> Would it be possible to make "m3c" close enough in syntax that some
> simple C header files could be processed?  Am I just being ridiculous
> now?  A compiler that can process both C and Modula-3 in the same
> file?
>
> Python, by the way, provides some interesting hooks for C programs
> to interact with the Python garbage collector.  Something similar
> could be done here.  (But there is far less reason to write C code
> to plug into M3 than there is to write it to plug into Python.)
>
>     Mika
>
>
> Darko writes:
>> If you like the idea, maybe you'd like join me in working out what
>> such a syntax would look like? Note that I want to keep the structure
>> the same, so no assignments in expressions, for example. Also, would C
>> programmers revolt at not having post and pre increment, also inside
>> expressions (as statements would be ok)? Requiring some sort of EVAL
>> statement? I guess the big question is whether removing these things
>> would make the whole idea unacceptable to the target audience. Does
>> the Algol syntax serve a purpose in making it clear that it isn't C?
>>
>>
>> On 16/02/2008, at 8:42 PM, Mika Nystrom wrote:
>>
>>>
>>> "If Steve Bourne could turn C into Algol using cpp, I'm sure you
>>> can figure out how to turn Algol[Modula] back into C using <...>"...
>>>
>>> If you think it would help acceptance of Modula-3, I don't see why
>>> not?
>>>
>>> I copied the code exactly the way it came off the old half-inch
>>> tape from Berkeley.
>>>
>>> Darko writes:
>>>> I'm not sure what you're getting at or if I'm missing something
>>>> witty.
>>>> I've said the form of the keywords makes little or no difference in
>>>> my
>>>> opinion. In my mail you quote I say there should be a C like syntax
>>>> for M3 as well as the existing one. I wasn't being sarcastic. It's a
>>>> matter of taste. I write in both all the time and it doesn't have any
>>>> impact on me, I go almost entirely by indentation, which I think is
>>>> very important. The indentation is pretty awful in code you posted
>>>> but
>>>> it could me my mailer.
>>>>
>>>> On 16/02/2008, at 10:51 AM, Mika Nystrom wrote:
>>> ...
>



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