Changes between Version 14 and Version 15 of DefaultSuperclassInstances

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Timestamp:
08/15/11 01:24:22 (22 months ago)
Author:
simonpj
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  • DefaultSuperclassInstances

    v14 v15  
    11= Default superclass instances = 
    22 
    3 A matter of much consternation, here is a proposal to allow type class declarations to include default instance declarations for their superclasses. It's based on [http://www.haskell.org//pipermail/haskell-prime/2006-August/001587.html Jón Fairbairn's proposal], but it has a more explicit 'off switch' and the policy on corner-cases is rejection. Credit is due also to the [http://www.haskell.org/haskellwiki/Class_system_extension_proposal class system extension proposal] and its ancestors, in particular, John Meacham's [http://repetae.net/recent/out/classalias.html class alias] proposal. 
     3A matter of much consternation, here is a proposal to allow type class declarations to include default instance declarations for their superclasses. It's based on [http://www.haskell.org//pipermail/haskell-prime/2006-August/001587.html Jón Fairbairn's proposal], but it has a more explicit 'off switch' and the policy on corner-cases is rejection. Credit is due also to the [http://www.haskell.org/haskellwiki/Superclass_defaults superclass defaults proposal],  [http://www.haskell.org/haskellwiki/Class_system_extension_proposal class system extension proposal] and its ancestors, in particular, John Meacham's [http://repetae.net/recent/out/classalias.html class alias] proposal. 
    44 
    55We may distinguish two uses of superclasses (not necessarily exclusive).