For reasons that are not easy to explain, no. [JSON] and '[JSON] have different meanings. Here, '[JSON] does not refer to a list of json files, but to a type-l

For reasons that are not easy to explain, no. [JSON] and '[JSON] have different meanings. Here, '[JSON] does not refer to a list of json files, but to a type-level list of the mimetypes that can be returned. You could see '[JSON, PNG] instead, which would make no sense in the context of a list type declaration. The genius of Servant is that the DSL doesn't require you to know how '[] is implemented and why it's different from [], you just have to know the DSL.