I’m writing a function that does some simple checks to see if a (crypto) wallet address can be considered valid for the specific network (validity of this aside; it’s more of a quick check to catch mistakes)

What I need to check:

1. Bech32 decode the provided address
2. This should result in a human-readable part (hrp) and a public key
3. The human-readable part should be either “rdx” or “tdx”
4. The total length of the public key should be 34
5. The first byte of the public key should be 4
6. The second byte of the public key should be 2 or 3

I’ve had multiple variations of this and none of them feel right. I was wondering if any of you had some suggestions on how to best write this function.

This is what I had first:

  def is_valid_wallet?(wallet_address) do
    {:ok, hrp, <<first_byte, second_byte, _rest::binary-size(32)>>} =
      Bech32.decode(wallet_address)

    if hrp in ["rdx", "tdx"] and first_byte == 4 and second_byte in [2, 3] do
      true
    else
      false
    end
  end

Problem with that is that I want to return true or false, and the pattern match might already return an error and I’m not handling that case. Adding the handling for that feels like I’m doing double work.

This is what I have now:

  def is_valid_wallet?(wallet_address) do
    case Bech32.decode(wallet_address) do
      {:ok, hrp, <<first_byte, second_byte, _rest::binary-size(32)>>}
      when hrp in ["rdx", "tdx"] and first_byte == 4 and second_byte in [2, 3] ->
        true

      _ ->
        false
     end
  end

This will return true or false, but it looks messy to me

Looking forward to hearing your suggestions.