Comment by regularfry
9 months ago
I believe that there is a genuine physiological effect that makes it a good idea to have the area of code that you need to think about fit entirely on one screen, without scrolling. There is probably an upper limit to the screen height where that limit is useful: I would believe a 100-line function to be above it and a 24-line function to be safely below it, but I wouldn't want to hazard a guess in the middle.
It's all to do with how your brain processes what it's seeing, and the planning processes involved in getting to the next bit of information it needs. If that information is off-screen, then the mechanisms for stashing the current state and planning to move your hands in whatever way necessary to bring it onscreen will kick in, and that's a sort of disfluency.
Similarly with tokens too far from whatever you're currently focused on. There's likely to be a region (or possibly a number of tokens) around your current focal point within which your brain can accurately task your eyes to scan, and outside that, there's a seeking disfluency.
I think this is why you get weird edge cases like k and j, where they pride themselves on having All The Code in one 80x24 buffer, and it actually works for them despite breaking all the rules about code legibility.
The term you're looking for is cognitive load. It's a qualitative term used to represent the amount of information a person has to keep in working memory while working on a task.
Cognitive load is part of it, but it's not the only part. If you want to scroll the page, you have to engage physical movement. That's an inefficiency in itself.
I agree. I once attempted this on a javascript project (a personal project, not at work), after reading about APL/J/K people and their philosophy. My constraint was: I should never have to scroll. I also aimed to have as few files as possible.
The result was surprisingly pleasant, and it changed how I feel about this sort of thing. I think the Clean Code approach makes a lot of sense when you are working on a big project that contains lots of code that other people wrote, and you rely on IDE features like jumping to definition, etc. But if you can write code that fits on one screen without scrolling, something special happens. It's like all the negative aspects of terse code suddenly vanish and you get something way simpler and overall easier to work with and understand. But you really have to work to get it to that point. A middle ground (terse code but still spread out over lots of files, lots of scrolling) would be the worst of both worlds.