Technology

I'm always suspicious of people who say that a language is suboptimal and use as evidence some filthy one-liner. Maybe if you bothered to write some whitespace and didn't write the language ignorant of its features (like generator expressions) you would end up with better code?

sum(
    all(
        abs(x) >= 1 and abs(x) <= 3 for x in line
    ) and (
        all(x > 0 for x in line) or
        all(x < 0 for x in line)
    )
    for line in diffs
)

You no longer have to "jump back and forth" except one single time - you have to look to the end to see where line is coming from and then you can read the body of the main expression from start to finish.

People don't, in fact, read code from top to bottom, left to right; they read it by first looking at its "skeleton" - functions, control flow, etc - until finding the bit they think is most important to read in detail. That implies that "jumping back and forth" is a natural and necessary part of reading (and hence writing) code, and so is nothing to fear.

There is still a slight advantage to not having to jump around, but consider the costs: in Javascript, map and filter are methods on Array and some other types. So how are you going to implement them for your custom iterable type? Do you have to do it yourself, or write lots of boilerplate? It's easy in Python. It's not bad in Rust either because of traits, but what this all means is that to get this, you need other, heavy, language features.

In practice, you often know what a comprehension is iterating over due to context. In those situations, having what the comprehension produces be the most prominent is actually a boon. In these scenarios in Rust/JS you are left skipping over the unimportant stuff to get to what you actually want to read.