Proposal: ExplicitForall

wren ng thornton wren at
Wed Jun 24 17:43:46 EDT 2009

Niklas Broberg wrote:
>  Simon Peyton-Jones wrote:
>> On ExistentialQuantification, I personally think we should deprecate the entire construct, suggesting GADT-style syntax instead.
> +1, though I was afraid to suggest something that radical. I might
> write a separate proposal for that then, to keep the discussion here
> focused on ExplicitForall.


There's the minor quibble that ExistentialQuantification is weaker and 
so using full GADT syntax allows writing types that can't fit into 
ExistentialQuantification. But I think removing the current wart is much 
better than introducing this minor one.

>> If you can form a consensus, go for it.
> Alright, let's set an actual discussion period of 2 weeks for
> ExplicitForall. If there is no opposition by then, we can add
> ExplicitForall to the registered extensions in cabal as a first step.

+1 to adding an ExplicitForall syntactic language pragma, as per your 
proposal (which implicitly enables it when using a semantic/type pragma 
that requires it).

Live well,

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