I’d not use that guarded version at all… Unicode has a lot of possible digits:

http://www.fileformat.info/info/unicode/category/Nd/list.htm

One doesn’t really have to iterate that list over and over again when using when char in @digits. Instead it should roughly like this:

@digits ~c[1234567890…] # include them all!

Enum.each(@digits, fn digit ->
  defp do_digit_only?(<<unquote(digit)::utf8, rest::binary>>), do: do_digit_only?(rest)
end
defp dp_digit_only?(<<_::utf8, _::binary>>), do: false
defp do_digit_only?(""), do: true

Numero 0.2.0 is released.

Hi everyone. Numero 0.2.0 is released.

In this version i have added two new functions.

• is_digit_only?/1 which checks if all of a string is numerical chars.
• remove_non_digits/2 which removes all non numerical chars form a given string with ability to have exceptions for some chars (optional).

I hope it will be useful for you guys.

Thanks.

@alisinabh: Here are my ideas:

1. Look at Naming Conventions: Trailing question mark (foo?)
2. I think that some things could be written simpler

For example:

defmodule Example do
  @digits String.graphemes("0123456789")

  def digit_only?(""), do: false
  def digit_only?(string), do: do_digit_only?(string)

  defp do_digit_only?(""), do: true
  defp do_digit_only?(<<char::binary-size(1), rest::binary>>) when char in @digits, do: do_digit_only?(rest)
  defp do_digit_only?(_), do: false
end

Thank you @Eiji for reminding me my problem with function naming. I should remove is_ from next minor version.

This example looks nice and clean but the reason i’ve done it with char list was so that i could determine utf-8 digits too (but now that is see my code i just forgotten to support utf-8 numbers ). like “۱” which is 1 in Farsi.

Dealing with binary operations is a UTF-8 string is a bit hard. and maybe ugly.
For example if i wanted to do as you did on numbers i should have done this:

defmodule Example do
  @digits String.graphemes("0123456789")

  def digit_only?(""), do: false
  def digit_only?(string), do: do_digit_only?(string)

  defp do_digit_only?(""), do: true
  defp do_digit_only?(<<char::binary-size(1), rest::binary>>) when char in @digits, do: do_digit_only?(rest)
  defp do_digit_only?(<<char::binary-size(2), rest::binary>>) when char in @digits, do: do_digit_only?(rest)
  defp do_digit_only?(_), do: false
end

Which i think may lead to some unwanted exceptions.

Any ideas on how to deal with them?

Thank you very much.

This is so helpful. I will try that soon.