When talking about lines of code written, "concise" is roughly "idea/length" whereas "expressiveness" is "sum of ideas", so yes, "concise" could be roughly seen as "expressiveness / LoC", but it's still the wrong word to use, as "expressiveness" specifically refers to the "breadth of ideas that can be represented and communicated". And either way, while the language spec is concise, the language itself is most definitely not