Changes between Version 27 and Version 28 of TypeFunctionsTypeChecking

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Timestamp:
08/22/06 14:07:58 (7 years ago)
Author:
chak
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  • TypeFunctionsTypeChecking

    v27 v28  
    5959                    | ClassTyCon    Class 
    6060                    | FamilyTyCon   TyCon     -- family tycon 
     61                                    [Type]    -- instance types 
    6162                                    TyCon     -- representation coercion 
    6263}}} 
    63 which is a generalisation of the old field `algTcClass` of the internal representation for datatypes, `TyCon.AlgTyCon`.  In contrast to the old `algTcClass` field, the new field also appears in `IfaceSyn.IfaceDecl`.  However, it does so as `Maybe IfaceTyCon` as we still do not want to represent class parent information in interfaces and we only record the family tycon in interfaces, not the coercion.  (The latter is implicitly reconstructed upon loading an interface.) 
     64which is a generalisation of the old field `algTcClass` of the internal representation for datatypes, `TyCon.AlgTyCon`.  In contrast to the old `algTcClass` field, the new field also appears in `IfaceSyn.IfaceDecl`.  However, it does so as `Maybe (IfaceTyCon, [IfaceType])` as we still do not want to represent class parent information in interfaces and we only record the family tycon and instance types in interfaces, not the coercion.  (The latter is implicitly reconstructed upon loading an interface.) 
    6465 
    6566NB: The type argument variables of the representation tycon are the free variables of the instance types; i.e., the representation data type is an ordinary data type, it is neither indexed nor open.  The only give away of its special purpose is the value in `algTcParent`.