Re: type variable lexical syntax

On 04/22/2013 10:09 AM, Michael Norrish wrote:
> On 22/04/13 4:29 PM, Andreas Rossberg wrote:
>> On Apr 22, 2013, at 03:31 , Michael Norrish
>> <[email protected]> wrote:
>>> Is the following really supposed to be acceptable? Both Poly/ML and
>>> mlton accept it without complaining:
>>>
>>> datatype '+ = C | D;
>>>
>>> (Moscow ML rejects it.  mlton and Poly/ML treat it as the
>>> declaration of a unary type operator called +.)
>>>
>>> and what about
>>>
>>> datatype '' foo = C | D;
>>
>> MLton and Poly/ML are correct. A type variable can be named plain '
>> or '', and symbolic identifiers (except *) are allowed as type
>> names.
>
> Wow; you learn something new everyday.
>
> Thanks for the quick feedback.
>
> Incidentally, I think that makes your grammar at
> http://www.mpi-sws.org/~rossberg/sml.html incorrect: the grammar there
> wants an <id> to follow the apostrophe for <var>, and <id>s have at
> least one character in them.

Yes, you are right. I was (semi-intentionally) sloppy there. Fixed.

Thanks,
/Andreas


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