Expose default static file loader

Part of #14.

example/z-playground/server/playground.ml

@@ -268,9 +268,7 @@ let () =
         Dream.empty `Not_Found
       else
         let%lwt response =
-          Dream__middleware.Static.default_loader
-            "static" "playground.html" request in
-        let response : Dream.response = Obj.magic response in
+          Dream.from_filesystem "static" "playground.html" request in
         Dream.with_header "Content-Type" "text/html; charset=utf-8" response
         |> Lwt.return);
 

src/dream.mli

@@ -1204,6 +1204,10 @@ val any     : string -> handler -> route
 val not_found : handler
 (** Always responds with [404 Not Found]. *)
 
+
+
+(** {1 Static files} *)
+
 val static :
   ?loader:(string -> string -> handler) ->
     string -> handler
@@ -1232,9 +1236,7 @@ val static :
       {!Dream.static}.
     - [path] is what was substituted for [**].
 
-    The default loader joins [local_directory] and [path], and uses the result
-    to respond with a file from the file system. If such a file does not exist,
-    the default loader responds with [404 Not Found].
+    The default loader is {!Dream.from_filesystem}.
 
     See example
     {{:https://github.com/aantron/dream/tree/master/example/w-one-binary#files}
@@ -1251,6 +1253,18 @@ val static :
     [ETag]}. See {{:https://developer.mozilla.org/en-US/docs/Web/HTTP/Caching}
     MDN {i HTTP caching}}. *)
 
+val from_filesystem : string -> string -> handler
+(** [Dream.from_filesystem local_directory path request] responds with a file
+    from the file system found at [local_directory ^ "/" ^ path].
+    If such a file does not exist, it responds with [404 Not Found].
+
+    To serve single files like [sitemap.xml] from the file system, use routes
+    like
+
+    {[
+      Dream.get "/sitemap.xml" (Dream.from_filesystem "assets" "sitemap.xml")
+    ]} *)
+
 
 
 (** {1 Sessions}

src/middleware/static.ml

@@ -14,7 +14,7 @@ module Dream = Dream__pure.Inmost
 (* TODO NOTE Using Lwt_io because it has a nice "read the whole thing"
    function. *)
 
-let default_loader local_root path _ =
+let from_filesystem local_root path _ =
   let file = Filename.concat local_root path in
   Lwt.catch
     (fun () ->
@@ -60,7 +60,7 @@ let validate_path request =
     else
       None
 
-let static ?(loader = default_loader) local_root = fun request ->
+let static ?(loader = from_filesystem) local_root = fun request ->
 
   if not @@ Dream.methods_equal (Dream.method_ request) `GET then
     Dream.empty `Not_Found