a String is a binary of UTF-8 codepoints
I confess, I HATE that line in the documentation because it’s explains virtually nothing and worse, I think it’s misleading (or at least, brutally confusing). Full disclosure: I’m trying to come up with a PR for that page that will help clarify the confusion around this.
A codepoint, as far as I understand, is a positive integer that corresponds to some character or control code in some “code space” – in our case, the code space is defined as the Unicode characters. So a “binary” in Elixir could be said to be a list of utf8-encoded codepoints (because it’s not actually a list of code points, but rather utf8’s encoding of the code point numbers). The way the sentence currently reads only makes sense if you already have a firm grasp on code points and encodings.
Relatedly, there is the confusingly named (in my opinion) String.codepoints/1 function which returns NOT the integer numbers (i.e. the code points), but instead the individual characters. I would expect String.codepoints("cät") to output [99, 228, 116] and not simply ["c", "ä", "t"]
So String.codeopints("cät") does nothing for us that String.split("cät", "", trim: true) wouldn’t give us already. In other words, there seems to be a lack of agreement as to whether a code point is the NUMBER or the CHARACTER. (Also, there doesn’t appear to be agreement between how to write code point (codepoint?), but that’s less important).
Why did Erlang use the term “binary” when it had other connotations?
