def Network.Wai.Middleware.select (choose : Request → Option Middleware) : Middleware

Conditionally apply a middleware based on a request predicate. If the predicate returns some middleware, apply it; otherwise pass through. $$\text{select} : (\text{Request} \to \text{Option Middleware}) \to \text{Middleware}$$

Equations

• Network.Wai.Middleware.select choose app req respond = match choose req with | some mid => mid app req respond | none => app req respond

theorem Network.Wai.Middleware.select_none : (select fun (x : Request) => none) = id

Select with always-none is the identity middleware. $$\text{select}(\lambda\, \_.\; \text{none}) = \text{id}$$