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

initial	v1
11	11	The 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.
12	12
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~~
	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's a case that does NOT have this problem:
14	14	{{{
15	15	-- C :: * -> * -> Constraint