Comprehending queries over finite maps

Recent programming languages research has developed language-integrated query, a convenient technique to seamlessly embed a domain-specific database query language into a general-purpose host programming language; such queries are then automatically converted to the language understood by the target DBMS (e.g. SQL) while at the same time taking advantage of the host language’s type-checker to prevent failure at run-time. The embedded query language is often equipped with a rewrite system which normalizes queries to a form that can be directly translated to the DBMS query language.