Here is v1 prototype to get a json spec from module docs. I also learned about running iex> c("MathOps.ex", ".") to compile the file.
defmodule MathOps do
@moduledoc """
This module provides math operations
"""
@after_compile {__MODULE__, :_build_json_def}
def _build_json_def(_env, bytecode) do
{:docs_v1, _, _, _, module_doc, _, docs} = Code.fetch_docs(__MODULE__)
{:ok, specs} = Code.Typespec.fetch_specs(bytecode)
defs =
for {{_, doc_name, _}, _, [sig], doc, _} <- docs,
{{spec_name, _}, [{:type, _, :fun, [{:type, _, :product, args}, {_, _, result, _}]}]} <- specs,
doc != :hidden,
doc_name == spec_name do
params =
for arg <- args,
{:type, _, type, _} = arg do
%{"type" => Atom.to_string(type)}
end
%{"name"=> Atom.to_string(doc_name), "doc"=> doc, "signature"=> sig, "params"=> params, "return"=> result}
end
document = %{"module"=> Atom.to_string(__MODULE__), "doc"=> module_doc["en"], "defs"=> defs}
IO.inspect(document)
end
@doc """
This function adds
"""
@spec add(integer, integer) :: map()
def add(a, b) do
%{"result" => Integer.to_string(a + b)}
end
end
Looks kinda bad in my opinion but it works 
. On compile it spits out clean looking map. Couple minor things yet and then json dump to file.
%{
"module" => "Elixir.MathOps",
"doc" => "This module provides math operations\n",
"defs" => [
%{
"doc" => %{"en" => "This function adds\n"},
"name" => "add",
"params" => [%{"type" => "integer"}, %{"type" => "integer"}],
"return" => "map",
"signature" => "add(a, b)"
}
]
}
Thinking later on this could be a mix compile task but haven’t learned about it yet.