I program, and am also presently working my way through some math books. I find that I often have to backtrack to look up pieces of notation like variables and operators. Unfortunately, this is very problematic. Greek and Latin letters give no indication of where they came from and are not usable search terms, even knowing the full context in which they appeared. Many authors have their own bits of idiosyncratic notation, often combinations of subscripting and line art generated by TeX macros. Since expanding equations out to their definitions is so difficult, I sometimes don't bother to investigate when one looks odd, which as you might expect leads to big trouble... (read more)
No, they aren't! You can't search to jump between the usages and definitions of a single-letter name, but you can jump between the usages and definitions of a full-word name, even if that name is blarghle.
Haskell can get away with this because it has strict, well-defined scoping rules which ensure that the names x and xs never appear too far from their definitions, and there is an algorithm which text editors can implement to find those definitions. Math books do not have either of those benefits.