Base class for parameter extractor objects, may be extended inline with chained ParamMapper objects.
A function Seq[String] => Option[B] used to test and transform values from the parameter map.
A function Seq[String] => Option[B] used to test and transform values
from the parameter map. Conditions may be chained with ~>
Maps first parameter, if present.
Construct a parameter predicate
Given a req, extract the request params into a (Map[String, Seq[String]], request).
Given a req, extract the request params into a (Map[String, Seq[String]], request). The Map is assigned a default value of Nil, so param("p") would return Nil if there is no such parameter, or (as normal for servlets) a single empty string if the parameter was supplied without a value.
Basic parameter access, and a pattern matching extractor in Extract.