I'm going to go ahead and offer a contrary viewpoint -- lining up code vertically makes it so much easier to read that the extra work involved
I haven't noticed it being easier to read, but I don't like syntax highlighting either, and lots of people seem to like that too. Taste is taste.
(trivial, if you have a half-decent text editor) is more than worth it. Also, if you're reading code in a proportional font, "you're doing it wrong."
The editor is 'acme', which a programming editor. It has support for fixed fonts too, but proportional is often more pleasant. You can fit a lot more on a line, but of course that can inconvenience the 80-column people :) It's worth a try if you haven't already. I think it's more than just half-decent, but it doesn't have any fancy vertical line up type features either. Anyway, it's definitely a minority use case, but that's a position haskellers should be used to :) And I admit I use a lot more fixed-width vim nowadays, so it's not a super big issue to me. But I do like it how everything looks nice when I occasionally do open up my project in acme because I miss some of its features. Vim and fixed width is especially ugly with unicode, so I'd think haskellers or agda-ists who appreciate a good pageful of cryptic math symbols to scare off the plebes would enjoy a nice proportional font using editor.