I have a following problem: I would like a new type of combinator in Servant (let's name it Provide): it would behave similarly to QueryParam, but instead of searching for a given param in a query string and passing it to the handler function, it would provide the value itself. For instance, let's say that we have something like
data Param = First | Second Int
type API = "url" :> Provide Param 'First :> Post '[JSON] SomeResp
server :: Server API
server = handler
handler :: Param -> Handler SomeResp
handler param = ...
so that handler will be always passed First as a param parameter. I know it can be done in other ways (like currying of the handler, etc.), but can it be achieved at the type level of the API itself?