[1mMain.hs:8.29-30:[1;31m error:[0m[1m
   • Could not deduce 'Eq Foo' arising from field 2 of constructor 'T' (type
     'Foo')
   • When deriving the instance for Eq (T a)
  [1;34m|[0m
[1;34m8[0m [1;34m| [0mdata T a = T a Foo deriving [1;31mEq[0m
  [1;34m|[0m                             [1;31m^^[0m

