A family of sessions constrained against each other.

Every other constraint in this library relates a session to a resource. A track is the first that does not: it says these sessions share an audience, so no two of them may run at once, and — if asked — a delegate must be able to walk between consecutive ones in the gap between them.

Not overlapping is intrinsic, not an option. A set of sessions that may collide with each other is just a list; what makes a track a track is that it cannot clash with itself. reachable/2 is the optional extra.

The word is deliberately not "stream": Elixir's Stream owns that name and a conference stream would shadow it at every call site.

Example

iex> import Tempo.Sigils
iex> keynote = Agenda.session("Keynote", duration: ~o"PT1H")
iex> deep_dive = Agenda.session("OTP internals", duration: ~o"PT1H")
iex> {:ok, track} =
...>   Agenda.track("Elixir", of: [keynote, deep_dive])
...>   |> Agenda.Track.reachable(within: ~o"PT10M")
iex> {length(track.sessions), track.reachable_within}
{2, ~o"PT10M"}

"No two talks in the Elixir track may overlap, and a delegate must be able to walk between consecutive ones inside the ten-minute break."

In iCalendar

iCalendar can say which sessions make up a track, but not what makes them one. An export writes two RFC 9253 properties on each of the track's sessions:

• REFID — the track's name, as text: the key that groups associated components, as an itinerary groups its legs.

• CONCEPT — a URI for the track as a classification, such as https://example.com/tracks/elixir, which the adapter mints from the track's name.

Both name the grouping, which is why the word stays Track. The rule is lost: iCalendar has no way to say that a track's sessions must not overlap each other, nor that a delegate must be able to walk between them (reachable/2). A track read back from iCalendar is a group of sessions that may clash.