[go-nuts] Map vs switch for lookup tables

I'm in the process of writing a package to validate and look up language
and region codes, and I'm trying to decide on which structure to use for
this. The tables will have 200 - 500 rows.

I tested various options and benchmarked them to get a feel for which would
be best, and (using a table with ±200 rows) I've narrowed it down to two
options.

1) Use a long switch statement. This has the advantage of not needing to
have a data structure in memory, and is fairly fast (67-87 ns/op).

2) Use a map which is preloaded in memory. This is a bit faster (38-50
ns/op), but has a long (relative time) to load up in memory of ±38 µs.

So, option 1 seems better for situations where it's called less often, and
2 seems better for situations where a longer setup time is okay, but the
function is called more often. I'm tempted to go with the switch method,
but before I commit to that, I'd like feedback on it, or pointers to any
other examples or methods that have been well executed.

~ John