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Comment by YZF | Hacker News Reader

I built a compiler for a simpler language as part of my compilers course in a CS degree. It was a non-trivial exercise well beyond the majority of software applications. What open source libraries did you have in mind and what are you copying?

If you can truly write a C compiler in weeks then kudos to you. How many compilers have you written so far for how many languages?

I work for big tech and I would say a large % of developers are incapable of producing a working C compiler on any reasonable time scale, certainly not weeks, even with looking at open source. I'm sure they can download one and run it. Most developers today don't even know C or assembler. They don't know how to approach the C language spec. The top 5-10% of developers/engineers can do it but even for them it's non-trivial.

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> It was a non-trivial exercise well beyond the majority of software applications

That depends on how you count. By number of programs that may well be right, but that's not what matters in terms of impact on the industry, as software value roughly corresponds to the number of people working on a particular piece of software (or lines of code, if you wish). By number of people/LOC most software is not in the "simpler than a C compiler" category.

I'd copy and paste from all the thousands of open source ones, what do you mean?

There are plenty of open source compilers that I can copy and paste whatever I need to. I don't get why you think this would have any level of difficulty?

Of course I couldn't make a brand new compiler that was better than what's out there...

Just like a game engine, I could clone one of the thousands of engines out there pretty easily - making something better or novel would be difficult. Just making a bare bones clone of what already exists by referencing documentation and pre-existing code is relatively easy now.

Yeah, when I made a mediocre 3d game engine 20 years ago, it was brain breaking difficult work. I can make one infinitely better in a micro fraction of the time now because most of the hard stuff is done and can just be looked up now.

Do you not agree?

If you copy and paste an entire compiler you didn't make anything. If you copy pieces from different compilers they won't work together. So I'm not sure how you "make" a compiler with copying and pasting from open source compiler. Are you saying you'll take one file from clang, one from gcc, another another from another compiler?

Sure. You can clone gcc and build it. You can close a game engine and use it.

> It was a non-trivial exercise well beyond the majority of software applications

Maybe if you include every application ever written, including every variation of "hello world", but if you are claiming that most serious production quality software could be written by a CS student who is simultaneously working on other classes, I'm gonna have to disagree with you.

I do think being able to write a compiler is a milestone indicator of your computer science knowledge. Most developers probably don't understand pointers either, because "most developers" are people who did a React bootcamp.

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