2.12 Virtual Hosts
The web-server/dispatchers/dispatch-host module defines a dispatcher constructor
that calls a different dispatcher based upon the host requested.
procedure
(make lookup-dispatcher) → dispatcher/c
lookup-dispatcher : (symbol? . -> . dispatcher/c)
Extracts a host from the URL requested, or the Host HTTP header,
calls lookup-dispatcher with the host, and invokes the
returned dispatcher. If no host can be extracted, then 'none
is used.