DSL (Domain Specific Languages) are, as the name implies, software development languages created for a specific niche or limited domain. Where could one use a DSL? For example, when writing a library to evaluate highly complicated financial products, it might be very beneficial to have a language designed to describe such products. The language will check correctness of a new product, will allow sharing of common pieces of definition, will be able to generate output that can be fed into other systems (risk calculation, trade processing, graphic representation).