All,

When XForms is lagging behind XPath, we find ourselves trying to reinvent things that have been already done. This is the case with the `transform()` function. So I wonder how much effort we should be spending on this given that there is such a function in XPath 3 and it does everything we need.

The thinking so far has been that we don't mandate XPath 3, and it would be nice if we could provide `transform()` anyway.

I think that is a valid approach, but only if:

1. The use cases for `transform()` are really strong.

2. It is reasonably easy to provide a `transform()` function without XPath 3 support.

Otherwise, I am tempted to say that efforts would be better spent updating to XPath 3.

So far the possibilities to add support include:

- providing a simplified `transform()` function, which e.g. doesn't support multiple inputs/outputs

- trying to use `xf:submission` (but it is unclear how to do that and whether that would be any easier)

- supporting what XPath 3 supports, but without XPath 3 maps

- with sequences

- embedding values and documents within XML

The last 2 sub-options have issues and in the end they are not quite equivalent to the XPath 3 version.

I mentioned during the last call last a 3rd possibility: provide very minimal support for maps, namely:

- a way to create an empty map (XPath doesn't seem to have a `map:empty()`)

- `map:put()`

- `map:get()`

- `map:keys()`

With this, if your XPath implementation supports custom functions and custom objects, you could create and pass a map to `transform()`, get a map back, and have something identical to the XPath 3 function.

With XPath 3, you would typically use the native map syntax:

let $result := transform(

map {

"stylesheet-uri" : "render.xsl",

"source-node" : doc('test.xml')

}

)

return $result?output//body

With XForms 2/XPath 2, you would instead use the functions above to create a new map:

map:get(

transform(

map:put(

map:empty(),

"stylesheet-uri",

"render.xsl"),

"source-node",

doc('test.xml'

)

"output"

)//body

The requirement is 4 small functions backing a basic implementation of maps, plus a function to create an empty map. The result would be source-compatible with the XPath 3 version, modulo maybe the namespaces for the `map:` functions.

It would do the job and be relatively usable, but is it worth it?

Regards,

-Erik