lennart at augustsson.net
Sat Feb 13 21:21:54 EST 2010
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.
> 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?
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