What are some things you wish you knew when you started programming?

The most important thing is not the code - it's the people that use the code. The more it helps people, the more valuable it is.

If you can afford the time cost, type out the code you were going to copy/paste from somewhere else. You'll get a better feel for what's happening as you type, allowing you to assimilate style conventions in with the rest of your codebase. The few typos you will likely make will force you to understand how exactly the code achieves goal.

Oh BTW, I answered a similar question in a comment a few weeks back -- I had more time that day, and I was able to give a more detailed answer:

See https://news.ycombinator.com/item?id=13713199

Also I've been posting a lot on math lately so if you want more examples and references, scroll through my HN posts and comments (I tend to cite everything so there's a ton of links in there).

Of special note, as others have started to discover, Grant Sanderson's 3Blue1Brown YouTube channel is a masterwork, an evolutionary tour de force in the way mathematical concepts and visualized and presented.

Grant wrote a custom software library (in Python, on Github) that enables him to create video visualizations to show the geometrical intuition behind abstract mathematical concepts. And this is key. Being able to visualize the geometric structure and transformations the mathematics is describing is the key that's been missing from the way math is traditionally taught, and this lack of visual intuition is why many find math so hard to penetrate.

3Blue1Brown's YouTube channel : https://www.youtube.com/channel/UCYO_jab_esuFRV4b17AJtAw

Go there first to develop your visual intuition -- watch all his videos, and then watch them again, and again -- and soon you'll discover your new, powerful mental models forming, and things that were once opaque will suddenly become clear.

Start with his "Essense of Linear Algebra" series (it's one people are usually blown away by, and it's being discussed on HN a bunch lately).

He's going to release an "Elements of Calculus" series in April, and while Calculus is usually a prerequisite to Linear Algebra, it's not critical for understanding the visualizations the way it's presented here. But if you need a refresher, MIT's "Big Picture Calculus" is great (it's linked to in the HN thread I referenced in the first paragraph).

I remember Shai from back in the ArsDigita days. ArsDigita and OpenACS were one of the first open-source projects I was involved with. Shai was one of the instructors at ArsDigita University -- one of the first CS courses on the Internet. ADuni began as an experiment by Phil Greenspun to see if it was possible to teach non-CS college grads the MIT Course 6 curriculum, compressed into a one-year, accelerated postbaccalaureate CS program.

https://en.wikipedia.org/wiki/ArsDigita

After the year ended, they released all of the video lectures online. This was back in the late 90s / early 2000s. Back then there was no YouTube, video compression sucked, and broadband was in its infancy so connections were painfully slow . To get the videos, you could try and download the massive video archive, but it took forever and I don't think I ever got the full thing. Finally at some point they started selling and shipping HDDs pre-loaded with the entire video archive.

http://aduni.org/courses/

Today we're fortunate to have a lot of high-quality course content available online. Greenspun was one of the pioneers who helped make that happen. We should all be thankful for his foresight and initiative to trailblaze that space.

http://philip.greenspun.com

Prior to ADuni, Phil put all the curriculum online for MIT 6.916 "Software Engineering for Web Applications". It was one of the first serious Web Engineering courses offered anywhere. Several other schools used the material to teach the course in their CS dept.

http://philip.greenspun.com/teaching/old-one-term-web-6916

Problem Set 4 was my favorite -- design a Knowledge Management (KM) system using metadata, and then let the computer generate the server-side code for the application automatically.

http://philip.greenspun.com/teaching/psets/ps4/ps4

The material was so new and innovative, it was the thing back in the day -- part of the foundational material programmers used as we were learning to build server-side apps in the dotcom era. The ArsDigita Community System (ACS) was one of the first big Web development toolkits, and it was built on top of AOLserver, a high-quality C server that had an embedded Tcl interpreter running inside. Greenspun is an MIT Lisp hacker, and Tcl is an embeddable language similar to Lisp. And running Tcl directly inside AOLserver was a key innovation because it made server-side scripts fast because it bypassed all the traditional CGI overhead, and it allowed you to make database calls from directly inside the server. All the architecture design choices were documented and explained in detail in "Philip and Alex's Guide to Web Publishing," which was required reading at the time.

http://philip.greenspun.com/panda/

The semester I did the self-study program, Phil had the MIT students take the final exam online via an app built on the ACS. The exam wasn't open to self-study students, but I wanted to take it for my own edification. I had become intimately familiar with the ACS code, and I found a way to to hack into the online system and took the exam under some guest account. I never found out how I did though -- I asked Phil about it one time when he came to Dallas, but he didn't remember. I can't believe that was almost 20 years ago.

I am learning that sometimes people try to defend their ideas by coming up with ways to make their idea work. If accommodating the solution is more work than actually implementing it, it might not be the right solution.