> vim can be used to replace a given text with another (eg show ⟹ instead of =>)
If you use the short ⇒ to substitute for => (rather than long ⟹ as in your example), as well as many other Unicode symbols, then the overall code can be much shorter and thus more understandable.
The spec for the Fortress programming language made a point of not distinguishing between Unicode tokens in the program text and the ASCII keys used to enter them. Perhaps that's the best way to go?
Why do you think that "much shorter" implies "more understandable"?
I think we have a lot of experience to suggest otherwise.
Anyone who has had to maintain old Fortran or C code will likely know what I mean. With some early implementations limiting variable and function identifiers to 8 characters or less, we'd see a proliferation of short identifiers used. Such code is by far some of the hardest to work with due to variable and function names that are short to the point of being almost meaningless.
Then there are languages like APL and Perl, which make extensive use of symbols. APL has seen very limited use, and Perl code is well-known for suffering from maintenance issues unless extreme care is taken when initially creating the code.
Balance is probably best. We don't want excessively long identifiers like is often the case in Java, but we surely don't want excessively short ones, either.
As somebody who spent some years writing Perl code, I don't feel that having a few well-defined ASCII symbols were such an issue. The problems with Perl are that symbols change depending on the context (eg, an array @items needs to be accessed via $items[$i] to get an item at position $i, to tell Perl it is a scalar context), and weak typing. Even with changing symbols, it makes it easier to distinguish between scalars, arrays and hashes, especially with syntax highlighting. As opposed to languages like Haskell or Scala, in which library designers are free to display their creativity with such immediately obvious operators as '$$+-'.
Edited to add that I agree with your overall point. Shorter is not always clearer. It can be a benefit to have a few Unicode symbols displayed via 'conceal' but it's not (at least in my experience) a major productivity gain. And the number needs to be kept small. If I want Unicode symbol soup, I'll play a roguelike.
If you use the short ⇒ to substitute for => (rather than long ⟹ as in your example), as well as many other Unicode symbols, then the overall code can be much shorter and thus more understandable.
The spec for the Fortress programming language made a point of not distinguishing between Unicode tokens in the program text and the ASCII keys used to enter them. Perhaps that's the best way to go?