Ask HN: How do you learn complex, dense technical information?

I come up with the smallest viable project I can think of that requires the given knowledge, that I'm also genuinely excited about building. I then try to get started, usually fail right away for lack of understanding of the "framework" parts of the problem, and then go off in search of examples, always keeping the goal in mind of getting my small project working.

I find this is applicable to a wide variety of subjects. I absorbed math in high-school with the mindset that I wanted to write a small theorem prover, for example.

In my ~20 years of experience, the only way to get good at something that is incredibly complex like kernel development, you will need to actually try to build the thing. Over and over and over. It doesn't matter what those reference manuals or books say. The computer doesn't give even the remotest feasible shit about the implementation reference or some particular author's opinion. Your tools do not know you are a noob trying to become a master. There is no gradient to follow that will allow you to meet this challenge in a fair way.

Many times, this frustration just boils down to cleverly-disguised subconscious procrastination. For me, the fear of trying to do the hard thing and failing at it is ultimately what keeps me from engaging certain things. This is a good sensibility to have so you don't bash your head against the wall, but sometimes you have to override it, start writing code, and accept that you will make some horrific mistakes. There is a light at the end of the challenge tunnel, that is if you actually begin to overcome it. This is one of the most addicting sensations I have experienced and I find it can carry me the rest of the way to mastery. That feeling you get when the browser actually loads your first web application, or when the ipsec VPN tunnel you've been fighting for days actually connects and you can ping both ways. Finishing a YouTube video or a chapter in some C kernel development book will never give you the same result.

> You can derive most things about as fast and more usefully than you can remember it. Except maybe a couple identities per area. But these will tend to be beautiful enough you will run over the derivation just for pleasure from time to time.

To derive things, you need to have memorized a basic set of theorems. As you go deeper and deeper, the "stack" gets bigger. If you only memorize the very basics, there's a good chance you will not be able to derive the deeper stuff whenever you need it.

If you are in second semester measure theory and you haven't ingrained a lot of the first semester of real analysis in your head, you likely will do poorly. Quick: When is a closed set not compact? If you do analysis a lot, you can easily answer this question. However, if you do it only occasionally, not knowing this will limit you (or even worse, and common, believing that all closed sets are compact).

I used to be in the camp of "Memorization sucks - just solve enough problems and it will stick". Its only recently that I'm realizing I was wrong. Everyone will have things stick if they do enough problems, but also everyone will have a different capacity for how much sticks. You'll hit your peak eventually by just solving problems, and a better memory will take you further beyond that small peak. Once you realize how effective SRS can be, you don't want to be limited by a poor memory.

> With enacs I find if it is not in my muscle memory it doesn’t matter if I consciously know about a feature. I can think “there must be some way of doing this” and then googling it and finding it as fast as I can stop my work

Often when reading the org mode manual I'll come across something that makes me say "Oh wow, I wish I knew this keybinding" and then would promise to remember it or look it up when needed. It's depressing how often I've said that about the same keybinding. Now that I use SRS, this phenomenon still occurs, but at less than half the frequency it used to.

Although to be frank, I now use hydra on Emacs often, so it's not as common for me to memorize keybindings.

> Especially now with everything changing so quickly I find paying attention to the deep constraints and reserving the possible solutions from those conditions is more effective than trying to memorize a bunch of library or platform specific capabilities.

Emacs is timeless :-) I will be using it for probably as long as I can use a computer.

But yes, I would be selective on what to put in SRS. Reviewing takes very little time, but creating new entries is time consuming. It needs to be worth it in the long run.

Another reason to use a library is once you write that left pad function yourself, you have to go copy it around from project to project whenever you need it, then fix or improve it and copy the changes all over again. Second time you do that, might as well pull it into a library. And now you have a library that you lug around, might as well host it somewhere. In a few short decades you roll your own package management infrastructure and fill it with all kinds of useful things like string concatenation subroutines and macros for flow control primitives built on jmp instructions and stuff like that.

Might as well shortcut all that and see if there is something in standard library or in an existing package...

Interestingly there is a concept in learning research called "desirable difficulties". The idea is that learning something, forgetting it and then struggling to learn it again leads to faster learning times. It may be that struggle is inherent in the process of learning something complex. If you equate struggle with pain, then I think it makes some sense. I have found that the best learners I know are also a little bit obsessive. They can't let go of a problem. So for them, the struggle in inherent in the way that they operate. For others, I think, the struggle can seem daunting. I think it's reasonable to suggest to those people that when learning something complex you are likely to place yourself in uncomfortable situations. However, it's important for those people to realise that the discomfort is not harmful and, in fact, can be challenging and rewarding.

Often I think it is quite similar to the situation where some people can not conceive of doing endurance sports. They view it simply as pain, or at the very best boring repetition. Others thrive on it. But if you want to learn how to enjoy endurance sports, it's probably a good idea to acknowledge that there will be times where you will be uncomfortable (possibly intensely so).