We are happy to announce that the following paper has been accepted in the 19th International Conference Implementation and Application of Automata (CIAA'14), to be held in Giessen, Germany, on July 30 -- August 2. A Type System for Weighted Automata and Rational Expressions Akim Demaille [1], Alexandre Duret-Lutz [1], Sylvain Lombardy [2], Luca Saiu [1,3] and Jacques Sakarovitch [3] 1 LRDE, EPITA; 2 LaBRI, Institut Polytechnique de Bordeaux; 3 LTCI, CNRS / Télécom-ParisTech https://www.lrde.epita.fr/wiki/Publications/demaille.14.ciaa We present a type system for automata and rational expressions, expressive enough to encompass weighted automata and transducers in a single coherent formalism. The system allows to express useful properties about the applicability of operations including binary heterogeneous functions over automata. We apply the type system to the design of the Vaucanson 2 platform, a library dedicated to the computation with finite weighted automata, in which genericity and high efficiency are obtained at the lowest level through the use of template metaprogramming, by letting the C++ template system play the role of a static type system for automata. Between such a low-level layer and the interactive high-level interface, the type system plays the crucial role of a mediator and allows for a cleanly-structured use of dynamic compilation.