Empty struct is good for representing non-nil zero-length information, for example this is ideal for many use cases where channels are involved. Or of you have

Empty struct is good for representing non-nil zero-length information, for example this is ideal for many use cases where channels are involved. Or of you have a http route and you want to return empty response(200 OK or 204 No Content, instead of error). Boolean on the other hand inherently contains two information: either true or false. ie. there will always be information and it will always be one of two values. This is similar to *struct{} where we can signal no information, or false, by returning/passing nil or initiated pointer to empty struct as true/value present. For maps, bool makes more sense as otherwise we just want a list with fast access to determine whether value in the list exists or not. Which is often something we might want. But it should not detract form the fact that each type has its own place and just because new implementation for maps ignores this, in this particular use, case does not make them worse than previous version. tl;dr it is good to know this fact about the new swiss maps, but it should not have any impact on programming an design decisions whatsoever.