F# Parsing XML, aiming to get to Type Providers

For a new project, I've started using some F# again. Type providers are brand new since last I used the language, so I thought I'd start out by writing my own type provider to deal with some xml apis I'll be using.

One of things I missed from F# was sequence generators. Here's a sequence generator that turns XML into a slightly different form, hopefully easier to consume from a type provider:

	//#module XmlTesting
	open System.Xml
	let xml = """
	<foo snark="boojum">
	<bar>
	<val t="somet" >tcontents</val>
	</bar>
	</foo>
	"""
	let r = XmlReader.Create(new System.IO.StringReader(xml))
	type SimpleNode = {
	name : string;
	ancestors : List<SimpleNode>;
	content : Option<string>;
	attributes : Map<string, string>;
	}
	let defaultNode = { name = ""; ancestors = List.empty; content = None; attributes = Map.empty }
	let xmlSeqOfAttributes (r: XmlReader) = seq {
	let buildAttr() = (r.Name, r.Value)
	let hasAttribute = r.MoveToFirstAttribute()
	match hasAttribute with
	| true ->
	yield buildAttr()
	while r.MoveToNextAttribute() do
	yield buildAttr()
	r.MoveToElement() |> ignore
	| false -> ()}
	let rec rdr ancestors : seq<SimpleNode> = seq {
	let hasEntity = r.Read()
	match hasEntity, r.NodeType with
	| true, XmlNodeType.Element ->
	let newNode = { name = r.Name; ancestors = ancestors; content = None; attributes = Map(xmlSeqOfAttributes(r)) }
	yield! rdr (newNode::ancestors)
	| true, XmlNodeType.Text ->
	let content = r.ReadContentAsString()
	yield { ancestors.Head with content = Some content }
	yield! rdr ancestors.Tail
	| true, XmlNodeType.EndElement ->
	yield ancestors.Head
	yield! rdr ancestors.Tail
	| true, _ -> yield! rdr ancestors
	| false, _ -> ()
	}
	and rdrStart = rdr(List.empty)
	let x = "---------------------------------------------"
	Seq.toList rdrStart

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Here's the output:

	val it : SimpleNode list =
	[{name = "val";
	ancestors =
	[{name = "bar";
	ancestors = [{name = "foo";
	ancestors = [];
	content = null;
	attributes = map [("snark", "boojum")];}];
	content = null;
	attributes = map [];}; {name = "foo";
	ancestors = [];
	content = null;
	attributes = map [("snark", "boojum")];}];
	content = Some "tcontents";
	attributes = map [("t", "somet")];};
	{name = "bar";
	ancestors = [{name = "foo";
	ancestors = [];
	content = null;
	attributes = map [("snark", "boojum")];}];
	content = null;
	attributes = map [];}; {name = "foo";
	ancestors = [];
	content = null;
	attributes = map [("snark", "boojum")];}]

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