(Disclaimer: I don’t work for Spotify)

Spotify is that really popular music streaming service most of you probably know about. If you’re familiar with the app you might also know that they give you lots of concepts to wrap your head around:

  • Playlist (A list of songs)
  • Albums (A list of songs corresponding to a record an artist has put out)
  • Artists (A list of albums the artist has worked on + a biography + related artists)
  • Folders (Can contain playlists and more folders)
  • Following (You can follow artists and playlists alike)
  • Favorites (Keeps track of your favorite songs)

These concepts are all useful in their own right but they do not work together very well. For example if I make a playlist of an album Spotify forgets the fact that it is an album altogether. Which means that when I play a song off the album page it’s not the same song as the song on my playlist of the album because the playlist is not the album. Confused? So am I.

I propose a unification of all these concepts by making everything a playlist:

Albums become playlists and can be used as such.

A folder is a set of playlists but also a playlist comprised of this set. This allows you to play music from the folder as a playlist when you want to, without losing the structure of all the separate playlists in the folder.

Artists also become playlists, where the playlist is updated every time the artist puts out a new record.

Want to keep track of your favorites? Simply create a playlist called favorites and put your favorite songs in there. No need for a separate ‘favorites’ concept.

Following is still very useful, allowing you refer to playlists by another artist, user, whatever and receiving updates to the playlist as well.

Set theory

If we look at set theory we can see many parallels with this new approach to playlists:

  • A folder is a union of the playlists inside it.
  • An artist’s playlist is the union of all the album playlists.
  • A playlist containing all songs off an album is a superset of the album’s playlist.
  • A playlist containing some (but not all) songs off an album is a subset of the album’s playlist.

Looking at it this way might not be immediately practical but it does show the compositionality of the playlist concept very well.

Conclusion

Designing anything, including software, should trigger us to think about how the different elements of the design complement each other. A beautiful design is often one comprised of a few parts that work well together. If the elements do not compose with one another a design can often feel like it has been put together in an ad-hoc fashion.

As with the Spotify app, we see that all these concepts like album, artist, playlist almost co-incidentally exist in the same space and are very weakly related. As if each concept was designed by someone else without thinking about the whole.

A unification and broad application of the playlist concepts neatly links everything together. The user only really needs to understand the concept of a playlist and all other concepts logically tie into it.