Port message manager to emulate a request-response style communication through ports, a'la Http.send ResponseHandler request.
Porter model, used to keep track of response handlers.
Module messages.
Update port model based on local messages. Returns a new port model and a local command that must be mapped to the parent message.
Subscribe to messages from ports.
Opaque type of a 'request'. Use the request function to create one,
chain them using andThen and finally send it using send.
Starts a request that can be sent at a later time using send,
and that can be combined using andThen.
Chains two Porter requests together: Run a second one right away when the first returns using its result in the request.
Sends a request earlier started using request.
Porter configuration, containing: