This is an interesting presentation from Bret Victor, with some great ideas for how we can support new kinds of data-driven visualisation in software design (with many implications for the design of other ‘programming’ tools): …
are fundamentally different than symbols, containers have a physical presence.
[…] the Pile object, and closed with the question, where does its z, which we will associate with the x- and y-coordinate at hand, come from? post 
The idea is to list one hundred curious things about programming. These can be taken on faith. In some languages they are true. In other languages, no. Developing a sense of what might and might not be true is the part of programming that is rarely taught, probably because the inconsistency is an embarrassment.