Ahoy

I am trying to add another filter to a diet template so that instead of 

   :javascript
      test();

I want to add something for doing WebGL programming, so my diet template would look like 

   :shaderfs
       test();

I have tried merely replicating the javascript blocks in http.server.d like 

static string filterShaderFS(I)(I text, size_t indent = 0)
{
	// added a simple return string here
	return "<script id=\"shader-fs\" type=\"x-shader/x-fragment\">" ~ '\t' 
		~ "precision mediump float;" ~ '\t' ~ "</script>";
}
...
static this()
{
	filters["css"] = (input, scope output) { output(filterCss(input)); };
	filters["javascript"] = (input, scope output) { output(filterJavascript(input)); };
	filters["markdown"] =(input,scope output) { output(filterMarkdown(cast(string)input)); };
	filters["htmlescape"] = (input, scope output) { output(filterHtmlescape(input)); };
	// added this in
	filters["shaderfs"] = (input, scope output) { output(filterShaderFS(input)); };
}

Also in vibe.templ.diet.d 

static this()
{
	registerDietTextFilter("css", &filterCSS);
	registerDietTextFilter("javascript", &filterJavaScript);
	registerDietTextFilter("markdown", &filterMarkdown);
	registerDietTextFilter("htmlescape", &filterHtmlEscape);
	registerDietTextFilter("shaderfs", &filterShaderFS); // added this in
}
...
foreach_reverse( f; filters ){
	bool found = true;
	switch(f){
		default: found = false; break;//break filter_loop;
		case "css": content = filterCSS(content, out_indent); break;
		case "javascript": content = filterJavaScript(content, out_indent); break;
		case "markdown": content = filterMarkdown(content, out_indent); break;
		case "htmlescape": content = filterHtmlEscape(content, out_indent); break;
 // added this in
		case "shaderfs": content = filterShaderFS(content, out_indent); break; 
	}
	if (found) filters.length = filters.length-1;
	else break;
...

static string filterShaderFS(string text, size_t indent)
{
	return "<script id=\"shader-fs\" type=\"x-shader/x-fragment\">" ~ '\t' 
		~ "precision mediump float;" ~ '\t' ~ "</script>"; 
}

I can't see any other locations that javascript is mentioned that is worth changing.

The code that implements the filters seems to my simple brain to be quite convoluted.

If I create a simple working app, then add in the shaderfs line 

doctype 5
html(lang="en")
	head
		title Uploader

		:shaderfs
			test();

		:css
			.test

I get the following 

[lots of log stuff]
...
webserver ~master: building configuration "application"...
Compiling Diet HTML template studio.dt...
studio.dt(7,20): Error: function vibe.http.server.staticTemplate!"studio.dt".staticTemplate.__lambda1.filter!(req, DefaultFilters).filter (const(char[]) input, string filte
r, void delegate(const(char[])) nothrow @safe output) is not callable using argument types (string, string, void)
../../../../../.dub/packages/diet-ng-1.1.3/diet-ng/source/diet/html.d(91,7): Error: template instance vibe.http.server.staticTemplate!"studio.dt".staticTemplate.__lambda1.c
ompileHTMLDietFile!("studio.dt", req, DefaultFilters).exec!(StreamOutputRange!(OutputStream)) error instantiating
../../../../../.dub/packages/vibe-d-0.8.0-beta.2/vibe-d/http/vibe/http/server.d(240,63):        instantiated from here: compileHTMLDietFile!(StreamOutputRange!(OutputStream
))
../../../../../.dub/packages/vibe-d-0.8.0-beta.2/vibe-d/http/vibe/http/server.d(163,6):        instantiated from here: render!("studio.dt", req)
source/webserver.d(25,13):        instantiated from here: staticTemplate!"studio.dt"
dmd failed with exit code 1.

Any pointers towards where I could look to get something like this working?
Are there other files I need to be considering?

Thanks in advance.
B