Regexp class parameter being understood as a String

{{class what (

  Regexp[/^.$/] $param,

) {

  notice('yes')

}

class { 'what':

  param => /^.$/,

}

$ puppet apply /tmp/z.pp 

Error: Evaluation Error: Error while evaluating a Resource Statement, Class[Classname]: parameter 'param' expects a Regexp value, got String at /tmp/z.pp:7:1 on node cwl.hostopia.com}}

{{$regexp = /^.$/

notice(type($regexp))

class foo($bar) {

  notice(type($bar))

}

class { 'foo': bar => $regexp }

Notice: Scope(Class[main]): Regexp[/^.$/]

Notice: Scope(Class[Foo]): String}}

# From <Volcane> 

function x(Regexp $thing) { notice(type($thing)) }