Proposal: Deprecate ExistentialQuantification

Niklas Broberg niklas.broberg at
Sun Jun 28 06:32:47 EDT 2009

>> In other words, in your 2x3 grid of syntactic x expressiveness, I want
>> the two points corresponding to classic syntax x {existential
>> quantification, GADTs} to be removed from the language. My second
>> semi-proposal also makes each of the three points corresponding to the
>> new cool syntax a separate extension.
> I see, but why are you opposed to have the classic syntax still support
> existentials (though foralls) and GADTs (through equality constraints). I
> would make sense to me to keep this support around.

I am opposed since
a) it requires the addition of extra syntax to the language, and
b) we have another, better, way to do it.

Somewhat pointed, I don't think the C++ way of putting all imaginable
ways to do the same thing into the language is a sound design
principle. If we have two ways to do the same thing, and one of them
is considered prefered, then I see no reason at all to keep the other
around. What I'm arguing here is that the GADT style syntax is truly
preferable, and thus the other should be removed.



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