[nightwolf]

The variable isn't mutated, actually — it's rebound. See http://natescottwest.com/elixir-for-rubyists-part-2/, for example.

[rdtsc]

Yes it is. x is the variable. It changed from 1 to 2. Mutation is a synonym for change. Try it yourself in the interpreter! So data is immutable, but variables are mutable in Elixir.

[andruby]

But if you passed that first x to a process, it would still be 1 even after you ran `x = 2`.