The Essence of Software: Why Concepts Matter for Great Design

by Daniel Jackson

Teabox, synergy and an amusing misfit. Teabox is a wonderful company that sells Indian teas directly to customers overseas. Their web app employed the synergistic composition I’ve described, in which free samples are added to the shopping cart as items with zero cost. This led to a funny anomaly. One time I was purchasing some of my favorite teas, and I entered a coupon code that Teabox had sent me previously. It did not give the discount that I expected. I eventually figured out what was going on. The coupon concept used a clever rule that didn’t just apply a percentage discount, but rather applied it to a maximum of three items in the shopping cart—and not just any three, but the three with the lowest prices. Two of these items, it turned out, were free samples. The remedy was to remove the free samples from the cart, after which the total cart price dropped precipitously, since two additional and much more expensive items were now being discounted. This is a nice example of a misfit (Chapter 5) in which a concept itself—in this case, the coupon concept—is perfectly plausible, but placed in an unanticipated context has undesirable behaviors.