Often an ad hoc programming language integrating features from different programming languages and paradigms represents the best choice to express a concise and clean solution to a problem. But, developing a programming language is not an easy task and this often discourages from developing your problem-oriented or domain-specific language. To foster DSL development and to favor clean and concise problem-oriented solutions we developed Neverlang. The Neverlang framework provides a mechanism to build custom programming languages up from features coming from different languages. The composability and flexibility provided by Neverlang permit to develop a new programming language by simply composing features from previously developed languages ...