Negation

[Lennart Augustsson]

I agree, I don't think this is a bug.  If the grammar actually says
that this is legal, then I think the grammar is wrong.


On Sun, Feb 14, 2010 at 1:48 AM, John Launchbury <john at galois.com> wrote:
> I don't think this is a bug. I do not expect to be able to unfold a definition without some syntactic issues. For example,
>
> two = 1+1
> four = 2 * two
>
> but unfolding fails (four = 2 * 1 + 1). In general, we expect to have to parenthesize things when unfolding them.
>
> John
>
>
> On Feb 13, 2010, at 11:56 AM, Simon Marlow wrote:
>
>> On 09/02/10 21:43, S. Doaitse Swierstra wrote:
>>> One we start discussing syntax again it might be a good occasion to
>>> reformulate/make more precise a few points.
>>>
>>> The following program is accepted by the Utrecht Haskell Compiler (here
>>> we took great effort to follow the report closely ;-} instead of
>>> spending our time on n+k patterns), but not by the GHC and Hugs.
>>>
>>> module Main where
>>>
>>> -- this is a (rather elaborate) definition of the number 1
>>> one = let x=1 in x
>>>
>>> -- this is a definition of the successor function using section notation
>>> increment = ( one + )
>>>
>>> -- but if we now unfold the definition of one we get a parser error in GHC
>>> increment' = ( let x=1 in x + )
>>
>> Now that *is* an interesting example.  I had no idea we had a bug in that area. Seems to me that it ought to be possible to fix it by refactoring the grammar, but I haven't tried yet.
>>
>> Are there any more of these that you know about?
>>
>> Cheers,
>>       Simon
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