Build failure with ghc 8.4

[DanBurton]

Building library for vinyl-0.7.0..
[ 3 of 11] Compiling Data.Vinyl.Core  ( Data/Vinyl/Core.hs, dist/build/Data/Vinyl/Core.o )

Data/Vinyl/Core.hs:229:10: error:
    • No instance for (Semigroup (Rec f '[]))
        arising from the superclasses of an instance declaration
    • In the instance declaration for ‘Monoid (Rec f '[])’
    |
229 | instance Monoid (Rec f '[]) where
    |          ^^^^^^^^^^^^^^^^^^

Data/Vinyl/Core.hs:233:10: error:
    • Could not deduce (Semigroup (Rec f (r : rs)))
        arising from the superclasses of an instance declaration
      from the context: (Monoid (f r), Monoid (Rec f rs))
        bound by the instance declaration at Data/Vinyl/Core.hs:233:10-70
    • In the instance declaration for ‘Monoid (Rec f (r : rs))’
    |
233 | instance (Monoid (f r), Monoid (Rec f rs)) => Monoid (Rec f (r ': rs)) where
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[acowley]

Thank you for letting me know! Version 0.8.1 should build against GHC-8.4.1.

[kirelagin]

I believe this was (properly) fixed in vinyl-0.9.1 (https://github.com/VinylRecords/Vinyl/commit/dd5d8849c2401271971c76b132a99b6d32745ca4).