In this paper we present how a domain-specific language, a language to program network firewalls, was embedded into the Haskell functional language.
The resulting embedded language gives systems administrators a language similar to the one they currently use, but with a richer syntax and semantics, with
many advantages over the original environment, such as the flexibility to extend and improve definitions of rule and constants. Also, there is no need for the systems
administrator to learn Haskell, or even to realise that he or she is using Haskell.