I've become very used to this in Mathematica. That takes it a little further: Matrices look like matrices, greek letters are actual greek letters and division w

I've become very used to this in Mathematica. That takes it a little further: Matrices look like matrices, greek letters are actual greek letters and division writes the parts as you'd see on paper - numerator over denominator. Any kind of mathematical code is vastly more readable this way. The way you access symbols is easy too: hit esc, type a short mnemonic, then hit esc again, for example esc-pi-esc gives you pi. Best of all, it's all stored as human-readable plaintext source under the covers. The display is just a convenience. Can't wait for unicode identifiers and this kind of expression composition in general purpose languages like objc.