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 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.