[ezrast]

Implementation-wise, yes, but the interface you're exposing is indistinguishable from that of a parser. For all your consumers know, you could be storing the username as a sequence of a 254-valued enum (one for each byte, except the angle brackets) and reconstructing the string on each "get" call. For more complex data you would certainly be storing it piecewise; the only reasons this example gets a pass are 1) because it is so low in surface area that a human can reasonably validate the implementation as bug-free without further aid from the type checker, and 2) because Go's type system is so inexpressive that you can't encode complex requirements with it anyway.