What is the theory behind mutable and immutable types?

Question

One of the things that I admire about Python is its distinction between mutable and immutable types. Having spent a while programming in c before coming to Python, I was astonis

Answer 1

If you like the idea of immutability, you should check out a pure functional language. In Haskell all (pure) variables are immutable (yet still referred to as "variables", but there you go). It is a great idea - you and the compiler both know that passing something into a function cannot change it in any way.