ceylon/ceylon-spec — Issue #149: Does principal rather than single instantiation inheritance require contravariant parameter types?
Author: gavinking
Created: 2012-01-23 15:25:43+00:00
State: open
Labels: clarification, high priority

See #148. Is there a way to write the rules to allow:

* invariant parameter types, with
* principal instantiation inheritance, or

do we need to change the spec to support contravariant parameter types. If so, how hard is this to implement in the compiler?