I found this very interesting. Specifically, I've never worked through implementing all the set operations in shell myself. You can see these as functional pro

I found this very interesting. Specifically, I've never worked through implementing all the set operations in shell myself. You can see these as functional programming, and you often represent sets and multi-sets as lists in fp. In shell, your elements just can't contain '\n'. Regarding the value of this, I see two main points: 1. When you're shell scripting (see next point ;-), you'll need some of these, and the situation might prefer not calling other programming languages. 2. The shell commands as used here are a fairly compact and convenient base for expressing these and many other computations. Many other environments would have a hard time representing computations processing more data than can fit RAM. Something comparable might be RDBMS-backed LINQ.