[Hugs] #90: type inference failure in ghc/hugs extensions

[Hugs]

#90: type inference failure in ghc/hugs extensions
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 Reporter:  guest                |       Owner:  nobody
     Type:  defect               |      Status:  new   
 Priority:  major                |   Milestone:        
Component:  hugs                 |     Version:  200609
 Keywords:  instance extensions  |  
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 Oleg recently posted on the mailing list
 haskell at haskell.org a magic coercion that makes pairs
 of numbers (x,y) behave as complex numbers.  Aside from
 context, the type should be (a,a).  The trick works with
 option -fglasgow-exts in ghc releases at least since 6.8.3.  However in
 hugs Sept 2006 under option -98, it fails type inference.  As I understand
 the documentation, option -98 is supposed to support the necessary
 extensions in common with ghc.

 Is the inconsistent handling of the attached fragment a bug,
 a feature, or perhaps an undefined corner of the semantics?

 Doug McIlroy
 doug at cs.dartmouth.edu

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Ticket URL: <http://hackage.haskell.org/trac/hugs/ticket/90>
Hugs <http://www.haskell.org/hugs/>
Hugs 98, an interpreter for Haskell