john at galois.com
Sat Feb 13 19:48:38 EST 2010
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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