7.4.1-pre: Show & Integral

wren ng thornton wren at freegeek.org
Mon Jan 9 05:36:19 CET 2012

On 12/22/11 2:28 PM, J. Garrett Morris wrote:
> 2011/12/22 Edward Kmett<ekmett at gmail.com>:
>> The change, however, was a deliberate _break_ with the standard that
>> passed through the library review process a few months ago, and is now
>> making its way out into the wild.
> Is it reasonable to enquire how many standard-compliant implementations
> of Haskell there are?

I believe the answer is (or on release of 7.4 will become) zero, unless 
UHC is fully compliant. I seem to recall that GHC already had other 
infelicities wrt the report, unless those had been fixed when I wasn't 

However, this is (to some extent) inevitable, because the haskell' 
process desires that things be already implemented before they are 
considered for inclusion in the new standard. IIRC, the desire to 
explicitly break from h2010 in this regard is as a preamble to getting 
the change into h2012 or h2013. Unfortunately, due to how typeclasses 
are defined there's no way to simultaneously implement the current 
standard and the desired new standard in such a way that the two will be 
able to interact (instead of duplicating all intersecting code so as to 
compile separately against both standards).

While the requirement to state Eq and Show is a burden wrt the old 
standard, it is fully compatible with it.

Live well,

More information about the Glasgow-haskell-users mailing list