A very bad one that can only be executed by brains with the requisite existing historical knowledge; in fact it's more like bad pseudo-code that lacks the explicitness necessary to translate into actual instructions. It's basically condensed jargon intended for the already converted.
It'd probably be vastly easier to teach math with an actual programming language than with traditional notation. Scheme would be ideal for this.
It's about the level of abstraction. And yeah if you don't understand the notation or syntax at the level of abstraction you're studying, it will be very hard.
(FWIW I find Scala code quite hard to understand sometimes, but I also find the more I know about the language, the more comprehensible it gets).
It doesn't matter how familiar you are with the language. Without an explanation of what the hell is going on, just looking at the code is useless.
Mathematical notation is basically a programming language. A programming language with weird symbols you can't type to search for, single letter variable names for everything, and no comments. And it's written by programmers that are obsessed with fitting everything into a simple line and making it as small as possible, no matter how difficult it is to read. Any programmer understands this is incredibly bad practice. And even if parse every step and perfectly follow what the code is doing, without explanation, it's pretty difficult to figure out why.