FailedFunctor.java

package co.coatomo.math.categorical.typeclass.functor;

import java.util.function.Function;

interface FailedFunctor<A> {

    <F extends FailedFunctor, B> F<B> map(Function<A, B> morphism);

}

javac output

$ javac -d /tmp co/coatomo/math/categorical/typeclass/functor/FailedFunctor.java 
co/coatomo/math/categorical/typeclass/functor/FailedFunctor.java:7: error: unexpected type
    <F extends FailedFunctor, B> F<B> map(Function<A, B> morphism);
                                 ^
  required: class
  found:    type parameter F
  where F is a type-variable:
    F extends FailedFunctor declared in method map
1 error