[mrkeen]

If you've wandered in from another language and are wondering what it might look like in a less terse language, here's an attempt:

    static IO<Integer> getSocketApiPort(@NotNull final Integer defaultPort) {
      return lookupEnv("socketPort")
        .flatMap((Optional<String> maybeEnvPort) -> {
          if(!maybeEnvPort.isPresent()) {
            return IO.of(defaultPort);
          } else {
            String strEnvPort = maybeEnvPort.get();
            Optional<Integer> envPort = readMaybe(strEnvPort);
            return IO.of(envPort.orElse(defaultPort));
          }
        });
    }