This syntax file displays unicode characters for some Python operators and built-in functions, turning the following:

    map (lambda x: x, [1,2,3])

    def foo(e, a):
        if e in [1,2,3] and not a:
            return math.sqrt(math.pi)
        else:
            return sum([1,2,3])

into

    map (λ x: x, [1,2,3])

    def foo(e, a):
        if e ∈ [1,2,3] ∧ ¬a:
            return √(π)
        else:
            return ∑([1,2,3])

Screenshot:

This does not – at any point – alter your source code. It simply uses Vim's "conceal" feature to “hide” in behind ∈, etc. Whenever the cursor is at a line with concealed text, the text will be expanded.

To install, simply put python.vim in ~/.vim/after/syntax or use something like Pathogen (recommended).

Vim ≥ 7.3 is required.

The branch moresymbols includes commits from various people that add even more conceal replacements. I try to maintain a healthy balance in the master branch, but if you like to conceal even more operators or don't mind slight inaccuracies in what mathematical symbols are used to represent, you should have a look at the extra symbols in the moresymbols branch.

This plug-in is very much inspired by http://github.com/Twinside/vim-haskellConceal