In Clojure, the adage says "When building DSL, favor data over functions over macros". When I write a DSL I start by writing a sample of it as pure data (think of Clojure as a data processing oriented language with embedded JSON (to be exact, the format is called EDN)). Then I write the parsing function. What I do though is to make sure the parser is extensible. To do so I cast any data element that this function parses into a corresponding function, except if that element is already a function. This way I can directly write custom functions within the DSL. This is very handy when handling conditions and their composition through function combinators. I can just reuse the language boolean logic (if, if-not, switch-cases etc) and don't have to reimplement it withing the DSL. Once the DSL data has been parsed into functions, they are then composed through classical function composition available in the language. Sometimes I also wish I had access to the DSL through macros, mostly to optmize those DSL. The situation I have found myself to need this required me to impact the compiler's state in some way, so I didn't carried my investigations forward regarding this subject, and I'm very interested in the development of Lux/luxlang since it comes with macros that are passed the compiler's state monadically.