[amw-zero]

There’s a lot of things wrong with this. First, this has nothing to do with the actual reason for the verbosity. The actual reason is that a value may or may not be present in a map, that’s a universal problem. Most languages just return nil or an Option value, but Go returns an error and forces you to handle it. No comment from me on whether that’s good or bad, but that’s the reason the code is like that.

The real problem is you’ve just made up a reason that the code is that way, and the reason is also crazy. No language purposefully makes something verbose simply to discourage doing it because of a performance concern. Even if they did, key lookups are constant-time complexity and are among the most efficient things you can do in all of programming. So that wouldn’t even make sense as something you’d want to discourage.

[rob74]

Err... Go does exactly what "most languages" do too! You can write:

    value, _ := map[key]

and if map[key] doesn't exist, value will be set to the "zero value" of the map's type. So Go doesn't force you to handle the error. The actual reason for the "verbosity" is just that you can't simply write

    if(map[key]) { ...

because map[key] returns two values (and "if" wants to have a boolean expression). But if you really have to do this so often that it's bothering you, you should question yourself why...

[jimsmart]

You can actually write:

  value := map[key]

and if map[key] doesn't exist, value will (still) be set to the "zero value" of the map's type.

The actual reason you cannot simply write:

  if(map[key]) { ...

aside from the extraneous parens, is because Go syntax does not permit implicit default values/truthiness in its 'if' statements like that (as you say "if wants to have a boolean expression"). That's the real reason for the verbosity here.

But you certainly can write:

  if map[key] != "" { ...

if the map contained strings, or:

  if map[key] { ...

if it contained booleans, etc. (For what that may be worth: checking for default value isn't the same as checking membership in all instances, of course).

Because map[key] can in fact return one — or two — values, depending on its usage context.

[amw-zero]

Go forces you to handle the error, which you agree with because you handled it by explicitly ignoring it via _.

[atom_arranger]

I was just speculating, this is the kind of thing I heard as justification for other things in Go.

I guess in this case the real reason is trying to force you to handle the error, and that the error and value are returned separately.