Yes, it is a shame people don't share their advances in science and technology for fear of losing market share usually. Sharing grows the market, and then there's more pie for everyone, and more work gets done to advance the field.
Still that point, nor how successful GP is in the ML community, measures its current or future potential. The book I am working my way through now, in LFE (Lisp Flavored Erlang vs. Erlang, or Elixir), is "The Handbook of Neuroevolution Through Erlang" by Gene Sher [1]
Gene covers a lot of ground. Somebody has done some transliteration to Elixir too; I use LFE, since staying with Lisp bridges the gap between my GP work, and what Gene has done with Erlang and ANNs and EC. For GP, you really need to be able to create new forms with macros, or it is more in line with GP. To quote and excerpt from Robert Virding, co-designer of Erlang, and creator of LFE,addressing Elixir's macros or messing with Erlang's modules vs. LFE's or Lisp's macros on HN before:
"There is syntactic support for making the function calls look less like function calls but the macros you define are basically function calls.
In Lisp you are free to create completely new syntactic forms. Whether this is a feature of the homoiconicity of Lisp or of Lisp itself is another question as the Lisp syntax is very simple and everything basically has the same structure anyway. Some people say Lisp has no syntax." [2]
