Use of Clojure macros for DSLs

Question

I am working on a Clojure project and I often find myself writing Clojure macros for DSLs, but I was watching a Clojure video of how a company uses Clojure in their real work an

Answer 1

No!

Don't be afraid of using macros extensively. Always write a macro when in doubt. Functions are inferior for implementing DSLs - they're taking the burden onto the runtime, whereas macros allows to do many heavyweight computations in a compilation time. Just think of a difference of implementing, say, an embedded Prolog as an interpreter function and as a macro which compiles Prolog into some form of a WAM.

And do not listen to those who say that "macros cant be applied or passed around", this argument is entirely a strawman. Those people are advocating interpreters over compilers, which is simply ridiculous.

A couple of tips on how to implement DSLs using macros:

• Do it in stages. Define a long chain of languages from your DSL to the underlying Clojure. Keep each transform as simple as possible - this way you'd be able to easily maintain and debug your DSL compiler.
• Prepare a toolbox of DSL components that you will reuse when implementing your DSLs. It should include target languages of different semantics (e.g., untyped eager functional - it is Clojure itself, untyped lazy functional, first order logic, typed imperative, Hindley-Millner typed eager functional, dataflow, etc.). With macros it is trivial to combine properties of all that target semantics seamlessly.
• Maintain a set of compiler-building tools. It should include parser generators (useful even if your DSLs are entirely in S-expressions), term rewriting engines, pattern matching engines, implementations for some common algorithms on graphs (e.g., graph colouring), etc.