Add Sitelet embedding combinator

[Tarmil]

Add a combinator to embed a Sitelet in another, more general type, for example if we have:

type EmbeddedAction =
    | // ...

type RootAction =
    | // ...
    | Embed of EmbeddedAction

then we want a combinator that allows to easily create a Sitelet<RootAction> given a Sitelet<EmbeddedAction>, which respects the original routing.

[endeavour]

This would be great. I did something similar here:
https://github.com/endeavour/websharperextensions/blob/master/WebsharperExtensions/SiteletModularity.fs

[Tarmil]

This is what I currently have in mind: https://gist.github.com/Tarmil/42d211300e09fde95b3b (example use and implementation)

[endeavour]

I'm not sure this is sufficient because you can't, for example, link back to the homepage from the embedded site.

i.e. You can't do this: inside Action1:
A [HRef (ctx.Link Home)] -< [Text "Go home"]

It would also be nice to use the parent templates in the child.

I found my original request for this feature (and your comments) here: http://fpish.net/topic/Some/0/76197

[Tarmil]

I think there is a use case for both:

• Embed can wrap an existing sitelet into a wider action type, where the existing sitelet doesn't need to know that it's going to be embedded.
• Your case, which I have just committed as InferPartial, where we want an inferred sitelet on a subset of the actions and the content function is aware of it.

With InferPartial your original request would be implemented as:

module NestedSite =
    let content templateWrapper = function
        | Foo -> templateWrapper <| fun ctx ->
            [
                Div [Text "Foo page"]
            ]
        | Bar x -> templateWrapper <| fun ctx ->
            [
                Div [Text "Bar page"]
            ]
        | Upload -> UploadHandler.UploadContentFactory "file" (fun _ -> "/success") (fun file -> () (*Save to disk etc here...*))

let Main =
    Sitelet.Sum [
        Sitelet.Content "/" Home HomePage
        Sitelet.Content "/About" About AboutPage
        Sitelet.InferPartialInUnion <@ Nested @> (NestedSite.content (Skin.WithTemplate "Home"))
    ]

[endeavour]

Great stuff :) Thanks.