I have another related question: What about allowing primitive types
in newtypes?
λ:4> newtype Blah1 = Blah1 Int
λ:5> newtype Blah2 = Blah2 Int#
<interactive>:5:23: error:
• Expecting a lifted type, but ‘Int#’ is unlifted
• In the type ‘Int#’
In the definition of data constructor ‘Blah2’
In the newtype declaration for ‘Blah2’
Ideally second definition should be OK, and kind of Blah2 should be #. Is this
too hard to do?
2015-12-16 17:22 GMT-05:00 Richard Eisenberg <e...@cis.upenn.edu>:
>
> On Dec 16, 2015, at 2:06 PM, Ömer Sinan Ağacan <omeraga...@gmail.com> wrote:
>>
>> In any case, this is not that big deal. When I read the code I thought this
>> should be a trivial change but apparently it's not.
>
> No, it's not. Your example (`f :: (Int#, b) -> b`) still has an unboxed thing
> in a boxed tuple. Boxed tuples simply can't (currently) hold unboxed things.
> And changing that is far from trivial. It's not the polymorphism that's the
> problem -- it's the unboxed thing in a boxed tuple.
>
> Richard
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