• simonpj@microsoft.com's avatar
    Add -XImpredicativeTypes, and tighten up type-validity checking (cf Trac 2019) · 5e04ae34
    simonpj@microsoft.com authored
    Somehow we didn't have a separate flag for impredicativity; now we do.
    
    Furthermore, Trac #2019 showed up a missing test for monotypes in data
    constructor return types.  And I realised that we were even allowing
    things like
    	Num (forall a. a) => ...
    which we definitely should not.  
    
    This patch insists on monotypes in several places where we were (wrongly)
    too liberal before.
    
    Could be merged to 6.8 but no big deal.
    
    5e04ae34
DynFlags.hs 62.1 KB