In F#, how to list the PrintQueues from the PrintQueueCollection? - printing

Question

(Newbie question).
I am attempting to list out the PrintQueues from the Microsoft PrintQueColletion in F#. Something like this:
let GetPrinters :List<PrintQueue> =
let localPrintServer = new PrintServer()
let printQueues = localPrintServer.GetPrintQueues [|EnumeratedPrintQueueTypes.Local; EnumeratedPrintQueueTypes.Connections|]
let printerList = printQueues |> ????
printerList
But I can't get how to turn the PrintQueueCollection into a list of PrintQueue.
Any suggestions will be most appreciated.
TIA
Hint: in C#, this is:
public static List<PrintQueue> GetPrinters()
{
PrintServer localPrintServer = new PrintServer();
PrintQueueCollection printQueues = localPrintServer.GetPrintQueues(new[] {
EnumeratedPrintQueueTypes.Local,
EnumeratedPrintQueueTypes.Connections });
var printerList = (from printer in printQueues
select printer)
.ToList();
return printerList;
}

Answer 1

UPDATE: See improved answer below this one.
This should do it:
let printerList =
printQueues
|> Seq.cast<PrintQueue>
|> Seq.toList
The trick here is that if you want printQueues to behave like an IEnumerable<PrintQueue>, you have to explicitly wrap it. This is what Seq.cast does.
(Side note: This is just one reason why having weakly-typed FooCollection classes instead of using built-in strongly-typed collections is a bad idea in general. Such is the legacy of old C# code.)

Answer 2

My first answer isn't technically correct, so I want to fix it here to make sure you see the update. It turns out that you don't need an explicit cast in this case, so the following simpler code will also work:
let printerList =
printQueues
|> Seq.toList
The rest of my explanation in the previous answer is correct for handling weakly-typed collections, but PrintQueueCollection is actually a strongly-typed IEnumerable<PrintQueue>, so it works just fine with the Seq module as it is. Sorry about that.