Refactor Chain function to use Middleware type

[72sevenzy2]

Add middleware type to slightly enhance readability.

[JRaspass]

I actually had a similar change locally and was considering PRing it, one fairly important different is I made it a type alias rather than a wholly different type so existing code would keep working, I also defined it just before the Middlewares type in chi.go as that seemed a more logical place:

+// Middlware is a type alias to standard middleware handlers.
+type Middleware = func(http.Handler) http.Handler
+
 // Middlewares type is a slice of standard middleware handlers with methods
 // to compose middleware chains and http.Handler's.
-type Middlewares []func(http.Handler) http.Handler
+type Middlewares []Middleware

After that there's a few more places that can be updated to use it like the Router interface, WalkFunc, etc. Just search and replace!

Not sure if such a change is wanted but it definitely gets my vote for being more readable, so long as it's just a type alias and therefore won't require explicit conversion from existing callers!

[72sevenzy2]

Thats actually smart, I never thought about that, thanks for giving me a heads up.

[VojtechVitek]

I was always hoping for Middleware type to be defined in net/http stdlib package :)

I don't think chi is the right place to reinvent this, though.

[72sevenzy2]

Oh I see.