About WFLP 2014 Preface The second part of this volume contains the papers presented at WFLP 2014: 23rd International Workshop on Functional and (Constraint) Logic Program- ming held on September 15-17, 2014 in Wittenberg, at the Leucorea Conference Center of Halle-Wittenberg University. The WFLP workshops series is running since 1992 and brings together re- searchers interested in functional programming, logic programming, as well as their integration. WFLP 2014 was jointly organized and located with WLP 2014: 28th Work- shop on (Constraint) Logic Programming. The WLP workshops series serves as the scientific forum of the annual meeting of the Society of Logic Programming (GLP e.V.) and brings together researchers interested in logic programming, constraint programming, and related areas like databases, artificial intelligence, and operations research. The technical program of the workshop included an invited tutorial by Michael Hanus on Declarative Multi-paradigm Programming, an invited talk by Sven Thiele on Answer Set Programming for Systems Biology, and presentations of refereed papers. I thank the invited speakers, authors of papers, programme committee mem- bers, external reviewers, as well as the local organizers Stefan Brass, Ramona Vahrenhold and Heike Stephan, for creating a very interesting and enjoyable workshop. September 4, 2014 Johannes Waldmann Leipzig Program Committee Elvira Albert Complutense University of Madrid Sergio Antoy Portland State University Mauricio Ayala-Rincon University of Brasilia William Byrd University of Utah Michael Hanus Universität Kiel Herbert Kuchen University of Münster Carlos Olarte Pontificia Universidad Javeriana Cali Peter J. Stuckey University of Melbourne René Thiemann University of Innsbruck Janis Voigtländer University of Bonn Johannes Waldmann HTWK Leipzig (chair) Additional Reviewers Maria Christakis Moreno Falaschi Keller, Gabriele Daniele Nantes-Sobrinho Ana Cristina Rocha Oliveira, German Vidal