Synchronous languages rely on formal methods to ease the development of applications in an efficient and reusable way. Formal methods have been advocated as a means of increasing the reliability of systems, especially those which are safety or business critical. It is still difficult to develop automatic specification and verification tools due to limitations like state explosion, undecidability, etc... In this work, we design a new specification model based on a reactive synchronous approach. Then, we benefit from a formal framework well suited to perform compilation and formal validation of systems. In practice, we design and implement a special purpose language (LE) and its two semantics the behavioural semantics helps us to define a program by the set of its behaviours and avoid ambiguousness in programs' interpretation; the execution equational semantics allows the modular compilation of programs into software and hardware targets (C code, Vhdl code, Fpga , synthesis, Verification tools). Our approach is pertinent considering the two main requirements of critical realistic applications: the modular compilation allows us to deal with large systems, the model-driven approach provides us with formal validation.