[dotancohen]

  > I actually am quite annoyed that most languages won't
  > let you use Greek characters as variables.

  $ python3
  >>> φ = 2
  >>> σ = 3
  >>> φ + σ
  5

[0x2c8]

This. Also, in IPython, one can write greek letters by doing:

    \Sigma<TAB>

which will get converted to an actual Σ.