Error found:
in module Main
at tests/purs/failing/ClassHeadNoVTA5.purs:10:15 - 10:29 (line 10, column 15 - line 10, column 29)

  No type class instance was found for
                       
    Main.MultiFdBidi t0
                     t1
                       
  The instance head contains unknown type variables.

  Note: The following type class members found in the expression require visible type applications to be unambiguous (e.g. tyClassMember @Int).
    Main.useMultiFdBidi
      One of the following sets of type variables:
        tyNotAppearInBody
        norThisOne

while checking that type forall (t20 :: Type) (t21 :: Type) (@tyNotAppearInBody :: t20) (@norThisOne :: t21). MultiFdBidi @t20 @t21 tyNotAppearInBody norThisOne => Int
  is at least as general as type Int
while checking that expression useMultiFdBidi
  has type Int
in value declaration multiFdBidi

where t0 is an unknown type
      t1 is an unknown type

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