Its all about the macros, man. If you are familiar with Erlang and gen_server, then perhaps looking at the examples in the readme of Exactor (https://github.com/sasa1977/exactor) will be enlightening to you. It presents a very straightforward DSL for defining gen_servers plus function wrappers in a very small amount of code with little boilerplate and repetition. There are other great libraries that make excellent use of macros, I just think this one makes this point really well.
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Its all about the macros, man. If you are familiar with Erlang and gen_server, then perhaps looking at the examples in the readme of Exactor (https://github.com/sasa1977/exactor) will be enlightening to you. It presents a very straightforward DSL for defining gen_servers plus function wrappers in a very small amount of code with little boilerplate and repetition. There are other great libraries that make excellent use of macros, I just think this one makes this point really well.