How do I avoid infinite recursion in a parser combinator

Questions & Help Questions
2

The answer came from Frerich on the elixir slack.

I’d gotten too far into think about the parsing aspect of the problem and didn’t see the purely functional aspect - eager vs lazy evaluation.

The solution in the end is simple, introduce an intermediate parser that sits between value() and list()

My first use of a macro in Elixir:

defmacro lazy(parser) do
    quote do
      Parser.new(
        :lazy,
        fn ctx -> Parser.invoke(unquote(parser), ctx) end
      )
    end
  end

Now I can write:

def value() do
  choice([
    number_value(),
    boolean_value(),
    string_value(),
    lazy(list_value())
  ])
)

And the recursion is broken.