Play query string DSL possibilities

dsl.scala

// In the path string:
case GET(p"/foo?param1=${param1}&param2=${param2}")
// Problems: doesn't support extracting lists of parameters or optional parameters

// Using ? and & extractors to combine multiple string interpolated query string parameters:
case GET(p"/foo" ? q"required=${required}" & q?"optional=${optional}" & q*"many=${many}")
// I think I like this one, q extracts String, q? extracts Option[String], q* extracts List[String]

// One question, how strict should we make it?

// Eg, we can do:
object ? { def unapply[A](a: A) = Some((a, a)) }
object & { def unapply[A](a: A) = Some((a, a)) }
// And then make the q, q? and q* extractors all take RequestHeader.

// Or, we could do this:
object ? { def unapply(req: RequestHeader) = Some((req.path, req.queryString)) }
object & { def unapply(qs: Map[String, Seq[String]]) = Some((qs, qs)) }
// And then q, q? and q* extractors can take Map[String, Seq[String]]

// And, we could implement q, q? and q* using a macro, validating the format of the
// extractor at compile time

Cool! I also like the second one better. Just FTR, you could also extend the first example with printf-style format specifiers

What about typed extraction?
Say, I want an orderId parameter to be a positive 32-bit signed integer?