checking package dependencies
compiling EFieldAmb.bs
Error: "EFieldAmb.bs", line 20, column 13: (T0018)
  The field `fst' is a member of multiple structs or interfaces, and there was
  not enough type information to decide which one is being referred to.
  Consider adding more explicit types, to help the compiler choose. The
  following structs/interfaces have a field named `fst':
    Prelude.PrimPair, EFieldAmb.My_pair1