We can either:

• Perform a single request, which will run the Porter Request and at the end turn the result into an a,
• Perform multiple requests: At the end of this request, run a function on the output that generates the next request. Note that this is set up in such a way that only the type of the final request in the chain matters.
• Short-circuit; just pass on the value a without doing any more requests.

Creates a new Porter.Multi request, specifying:

• the request itself in the common req type
• A response handler function tha turns the common res type into a specialized a.

Actually sends a (chain of) request(s).

A final handler needs to be specified that turns the final result into a msg. This msg will be called with the final resulting a once the final response has returned.

Turns a simple Porter request into a Porter.Multi request

Combines together multiple Porter.Multi requests

andThenResult function similar to andThen, but will short-circuit the request/response chain once an Err val is received.

Working with Result-objects is very common, since the specialising of res -> a (that you pass to request) is usually an operation that might fail (like a Decoder)

Turns the request's specialized response type into a different type.

Chains two requests, and then combines their two responses into one new c.

Chains three requests, and then combines their three responses into one new c.