Error found:
at tests/purs/failing/MissingClassMember.purs:9:1 - 10:10 (line 9, column 1 - line 10, column 10)

  The following type class members have not been implemented:
  b :: String -> Number
  c :: forall f. String -> f String

in type class instance
               
  Main.A String
               

See https://github.com/purescript/documentation/blob/master/errors/MissingClassMember.md for more information,
or to contribute content related to this error.