Changes between Initial Version and Version 1 of Ticket #14331, comment 28


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Timestamp:
Oct 19, 2017 2:22:44 PM (2 years ago)
Author:
simonpj
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  • Ticket #14331, comment 28

    initial v1  
    1111The quantified variables of the data type decl can freely be instantiated in the (derived) instance.  We want the most general such instantiation so that the derived instance is applicable as much as poss; hence unification.
    1212
    13 I have belatedly realised that the real stumbling block here is when the same variable appears ''both'' in the data type decl ''and'' in the `deriving` clause.  For example here
     13I have belatedly realised that the real stumbling block here is when the same variable appears ''both'' in the data type decl ''and'' in the `deriving` clause.  For example, here's a case that does NOT have this problem:
    1414{{{
    1515-- C :: * -> * -> Constraint