Allow derive newtype instance for newtypes that use type synonyms #2481

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1. paf31 commented on Dec 14, 2016

   

   paf31

   on Dec 14, 2016

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   I thought this was the same bug as #2416. How is it different?
2. joshuahhh commented on Dec 14, 2016

   

   joshuahhh

   on Dec 14, 2016

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   @paf31: #2416 is about deriving instances of Newtype for newtypes which use type synonyms, like

   type MyString = String
   newtype WrappedString = WrappedString MyString
   derive instance newtypeWrappedString :: Newtype WrappedString _
   

   #2481 is about deriving newtype instances (via derive newtype instance) of other typeclasses for newtypes which use type synonyms, like

   type MyString = String
   newtype WrappedString = WrappedString MyString
   derive newtype instance semigroupWrappedString :: Semigroup WrappedString
   

   I don't actually know what's going on behind the scenes here, so these may be the same problem at a deeper level.

   But #2416 is, literally speaking, just about a failure to derive instances of capital-N Newtype, so I thought this might be something new.
3. paf31 commented on Dec 14, 2016

   

   paf31

   on Dec 14, 2016

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   I thought it was the other way around. Either way, the other issue is #1443, and I think this duplicates one or the other.
4. garyb commented on Dec 14, 2016

   

   garyb

   on Dec 14, 2016

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   The other issue is not #1443, as we discussed before 😛, although once the other issue is fixed, 1443 will probably become a problem too. This one is definitely closer to #1443, and maybe will be fixed by the same thing.
5. paf31

   added

   type: bug

   typechecker

   on Dec 21, 2016
6. paf31

   added this to the 1.0 milestone on Dec 21, 2016
7. paf31

   closed this as completedin #2516on Jan 1, 2017