[GHC] #1245: Turn tuples into syntactic sugar for heterogeneous lists

[GHC]

#1245: Turn tuples into syntactic sugar for heterogeneous lists
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    Reporter:  benja.fallenstein at gmail.com  |       Owner:         
        Type:  feature request              |      Status:  new    
    Priority:  normal                       |   Milestone:         
   Component:  Compiler                     |     Version:  6.6    
    Severity:  normal                       |    Keywords:         
  Difficulty:  Unknown                      |    Testcase:         
Architecture:  Unknown                      |          Os:  Unknown
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It would be nice if (x,y,z) were syntactic sugar for a
 [http://homepages.cwi.nl/~ralf/HList/ heterogeneous list], i.e. (x :*: y
 :*: z :*: HNil) where

 {{{
 data a :*: b = a :*: b
 data HNil = HNil
 }}}

 (:*: associating to the right). Using functional dependencies and the
 techniques from the HList paper, we could then process tuples of arbitrary
 length in a uniform matter: for example, the Data.Monoid.Monoid instances
 for tuples. At the same time, this would create a slightly more light-
 weight syntax for heterogeneous lists, making them more acceptable for use
 cases like functions with optional or keyword arguments.

 I'm not sure how much existing code would this would break. Showing and
 reading heterogeneous lists as tuples doesn't seem hard to implement. I
 don't know about Typeable and friends.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1245>
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