Functional Programming
A functional program is one with no side effects:
If we call sin(x), it will just return a value, but will have no side effects.
Functional programming does everything by composition of functions:
guacamole:
season(mash(slice(peel(wash(avocado)))))
Functions are composed so that the output of one function is the input of the next function.
Functional programming works well with distributed cloud computing: the function can be replicated on many servers and executed in parallel on massive amounts of data.