Another question

[jxxcarlson]

First off - is there a better forum for my questions? They are not issues with Combine, but rather are problems due to my lack of experience. I very much appreciate your help and will try to keep questions to a bare minimum as I learn Combine.

The problem. The parsing functions that I write work in isolation but not when I combine them. Here is an example (in module MU.Parse):

  def str2(input) do
    parser = take_while(fn(a) -> !Enum.member?('-=+*\n\r', a) end)
    input |> Combine.parse(parser)
  end

And here is verification that it works:

iex(6)> MU.Parse.str2("foo\nbar")
['foo']

But when I try to use Parse.str2 inside Combine.parse, I get an error:

iex(1)> use Combine
Combine.Parsers.Binary

iex(2)> MU.Parse.str2("foo-bar")
['foo']

iex(4)> Combine.parse("[foo bar]", sequence([char("["), MU.Parse.str2(), char("]")]))
** (UndefinedFunctionError) function MU.Parse.str2/0 is undefined or private. Did you mean one of:

      * str2/1

    (mu_server) MU.Parse.str2()

There seems to be an arity problem, but MU.Parse.str2 in place of MU.Parse.str2() doesn't work either.

[bitwalker]

First, you can always open issues for questions here, it helps others who come after :)

Your problem here is that you need to remove Combine.parse/2 from the str2 implementation. It will then return a parser which can be combined as you are trying to do. Combine.parse/2 expects specifically implemented parser functions, which you can easily implement, but are not the same as plain functions. If you are interested in implementing parser functions, take a look at defparser and Combine's implementation of some of the various parsers.