Help with sets

[nn]

> Semantic web.  I did get a bit confused in reading about the concept of
> sets in python and why you would use them instead of a dictionary for

Sets are faster and more convenient to do intersections, unions,
differences. They also use less space than dictionaries. Finally they
also help conveying the intent of the code.

Many things can be emulated using dictionaries. In languages like Lua
there are no sets, and no tuples, and no lists*. This makes sense if
your goal is to create a very small embedded language. Using specific
structures on the other hand has the benefit that operations common to
that structure are more convenient to express and that those
operations are optimized for space and time.


*"Tables are the sole data structuring mechanism in Lua; they can be
used to represent ordinary arrays, symbol tables, sets, records,
graphs, trees, etc." http://www.lua.org/manual/5.1/manual.html#2.2