Changes between Version 6 and Version 7 of PolymorphicKinds


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Timestamp:
Oct 17, 2008 9:11:51 AM (7 years ago)
Author:
simonpj
Comment:

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  • PolymorphicKinds

    v6 v7  
    104104 * This makes it hard to add additional constraints to the k in future (sort annotations, kind classes?)
    105105
    106  * A typo with a rank-n kind could be very confusing, e.g.
    107  
    108 {{{
    109 #!text/x-haskell
    110   f :: forall (m :: k -> (forall k . k' -> *))
    111 }}}
    112 
    113 
     106Just occasionally, a Haskell program ''needs'' an explicit kind signature, because the defaulting mechanism makes the wrong choice:
     107{{{
     108data T m = MkT    -- m defaults to (m::*)
     109}}}
     110Suppose you really wanted
     111{{{
     112data T (m::*->*) = MkT
     113}}}
     114Question: could the same thing happen at the next level up, so that we want explicit sort signatures?  And if so, does that mean we need explicit binding sites for kind variables?
    114115
    115116== Type Classes ==