Changes between Version 450 and Version 451 of TypeFunctionsStatus

Jul 24, 2009 8:34:54 AM (5 years ago)



  • TypeFunctionsStatus

    v450 v451  
    77 * Declarations involving families: 
    8   * Can we add a warning in case of a signature that is ambiguous due to a type variable only been mentioned as an argument to a type synonym family? 
     8  * If a type variable occurs only in arguments to type synonym families in a signature, GHC ought to reject the signature as ambiguous.  (If the variable is mentioned in an argument to a type class in the context, we cannot reject it though, as the class may contain a TF or FD that constrains the variable.) 
    99  * #2435 (Inconsistency in handling qualification of names of class methods and associated types in instance declarations) 
    1010  * Defaults for associated type synonyms.  (Having both a kind signature and vanilla synonym is problematic as in `RnNames.getLocalDeclBinders` its hard to see that not both of them are defining declarations, which leads to a multiple declarations error.  Defaults are quite different from vanilla synonyms anyway, as they usually have tyvars on their rhs that do not occur on the lhs.)  If an associated synonym has a default definition, use that in the instances.  In contrast to methods, this cannot be overridden by a specialised definition.  (Confluence requires that any specialised version is extensionally the same as the default.)