[bitc-dev] Value types and the Value restriction
Jonathan S. Shapiro
shap at eros-os.org
Sun Aug 6 14:18:29 EDT 2006
I think that your approach on this, which you described in:
It would be useful if you could send out a followup note that follows
the following outline, so that everybody shares a coherent picture:
I. The Problem
Give an example of something that is screwed up under the
current type rules. Explain why it's a problem.
II. The Proposal
Say what the plan/solution is. What are the new rules?
Give some examples that will produce different answers
under the old and new rules, so that people can see them.
Finally, can you either define what you meant by "contrapositive
position" or perhaps use "contravariant position" (which is what I think
you meant). Note that contravariance has a weird odd/even inversion for
function parameters, so if you mean contravatiant that's great, but you
should check whether what you mean is "argument position". For example,
are there also issues in covariant position?
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