Advanced Compilers: Self-Guided Online Course • Hacker News Board

Re: Advanced Compilers: Self-Guided Online Course

#181

Post by ibains » Sat, Dec 12, 2020, 5:44 AM UTC

bachmeier wrote: post #76

ibains wrote: post #59

I’ve worked on multiple compilers (optimizations expert) at MSFT on VS and CUDA and gave developed a DSL and worked on Database Compilers. I can’t hire compiler people with right skills. We’re building an IDE and those parsers are written differently, and we use Scala packrat parser combinators. These courses teach very little judgement or industry relevant stuff. When do you use packrat parser vs LALR vs LL? Good lu…

> I’d like to sit down all university professors who teach compiler courses and teach them a course on what’s relevant. I don't teach compiler courses, but I'm an academic, and I do keep in touch with industry people to find out what's important for my data analysis course. A couple of big problems with your proposal: 1. Time variation in "what industry wants". This year one thing's hot, the next year it's something…

There is no such variance and new fashions in compilers every year. There are hardware compilers and tools including language servers primarily. Move to cloud requires source to source compilers for data snd transforms.

Re: Advanced Compilers: Self-Guided Online Course

#182

Post by ibains » Sat, Dec 12, 2020, 5:48 AM UTC

seanmcdirmid wrote: post #81

ibains wrote: post #59

I’ve worked on multiple compilers (optimizations expert) at MSFT on VS and CUDA and gave developed a DSL and worked on Database Compilers. I can’t hire compiler people with right skills. We’re building an IDE and those parsers are written differently, and we use Scala packrat parser combinators. These courses teach very little judgement or industry relevant stuff. When do you use packrat parser vs LALR vs LL? Good lu…

You are thinking about it the wrong way. In this niche, you will almost never find people with the exact skills you are looking for. Better to find people with tangentially related skills and experience and let them grow into the role. Academia is never going to be comprehensive enough to prepare students for every niche that has some demand. Rather, they should just focus on teaching a core that will help them learn…

packrat parser combinators are recursive descent with infinite look ahead. That’s the problem, engineers are under educated

Re: Advanced Compilers: Self-Guided Online Course

#183

Post by TACIXAT » Sat, Dec 12, 2020, 6:01 AM UTC

chrisseaton wrote: post #94

carom wrote: post #84

Earlier quoted context omitted.

Is that such a critical hiring criteria? That seems like something I could learn in a week.

> That seems like something I could learn in a week. So why not learn it in a week then apply for the job? I would suggest the reason is... because you cannot learn it in a week.

>So why not learn it in a week then apply for the job?

For a lot of reasons. I'm not looking to work in compilers. OP sounds like the opposite of the type of people I want to work with. I enjoy what I work on quite a bit. I am paid well. I have the chance to build up the business and a team.

It is just an attitude that I see a lot. The candidate doesn't have XYZ specific knowledge. Find someone who is interested and motivated (e.g. someone who has independently taken an advanced course in a topic) and build them up.

I'm sorry that some candidate can't answer your trivia question, but if it could be taught in a 16 week course (~10 hours / week), you could find a way to convey it on the job (~40 hours / week) in a much shorter period of time.

For this scenario have new hires work through a series of designed problems. Have them implement and run into the pitfalls with LL, LR, and Packrat parsers. Show issues with left recursion, shift / reduce conflicts, space trade offs of Packrat, seriously whatever you want to demonstrate.

Even just write up a document explaining when to use each rather than bemoaning the lack of knowledge. Like how much cooler would the top comment in this thread have been if I had learnt something?

This feels a lot like "I want a candidate with the knowledge of a senior for the price of a recent grad".

Re: Advanced Compilers: Self-Guided Online Course

#184

Post by zerr » Sat, Dec 12, 2020, 6:12 AM UTC

ibains wrote: post #59

I’ve worked on multiple compilers (optimizations expert) at MSFT on VS and CUDA and gave developed a DSL and worked on Database Compilers. I can’t hire compiler people with right skills. We’re building an IDE and those parsers are written differently, and we use Scala packrat parser combinators. These courses teach very little judgement or industry relevant stuff. When do you use packrat parser vs LALR vs LL? Good lu…

Unless you're looking for an external consultant for the one month project, you're doing it wrong: https://www.reddit.com/r/ProgrammerHumor/comments/4k994j/if_...

Re: Advanced Compilers: Self-Guided Online Course

#185

Post by bird_monster » Sat, Dec 12, 2020, 6:25 AM UTC

ibains wrote: post #59

I’ve worked on multiple compilers (optimizations expert) at MSFT on VS and CUDA and gave developed a DSL and worked on Database Compilers. I can’t hire compiler people with right skills. We’re building an IDE and those parsers are written differently, and we use Scala packrat parser combinators. These courses teach very little judgement or industry relevant stuff. When do you use packrat parser vs LALR vs LL? Good lu…

> I’d like to sit down all university professors who teach compiler courses and teach them a course on what’s relevant.

I'm sorry if you've already answered, or if it comes up a lot, but could you toss up some buzzwords/more industry-standard things you're looking for? I was going to look into this course, and still probably will, but if you're saying it's not relevant I'd like to know what to be looking into instead?

Re: Advanced Compilers: Self-Guided Online Course

#186

Post by jonnytran » Sat, Dec 12, 2020, 6:44 AM UTC

mafribe wrote: post #126

ibains wrote: post #59

I’ve worked on multiple compilers (optimizations expert) at MSFT on VS and CUDA and gave developed a DSL and worked on Database Compilers. I can’t hire compiler people with right skills. We’re building an IDE and those parsers are written differently, and we use Scala packrat parser combinators. These courses teach very little judgement or industry relevant stuff. When do you use packrat parser vs LALR vs LL? Good lu…

I understand the problem. I teach compilers at a big university. And I would love to hire graduates with compiler skills for my startup, but find it difficult. There are several structural problems that conspire to keep students from acquiring knowledge in low-level programming domain like compilation: a course needs to fit with the rest of the curriculum, and with student interest. I cannot get students interested i…

I never understood this. I took the compilers class at CMU, and I loved it. I went on to take a follow-up class implementing a compiler with higher-order types. Meanwhile, most of my classmates avoided compilers altogether.

I've worked in the industry since undergrad, and I've implemented several interpreters for DSLs. Sometimes I was asked to make it, but other times I had the flexibility to dream up a DSL on my own, and it ended up becoming indispensable to users. I've always loved building them, but to this day, parsing is still the most boring part to me.

I recently went through Bob Nystrom's Crafting Interpreters, and it was great fun. I implemented an interpreter in Rust. Material about compiling for GPUs would be interesting. But for me, personally, I really wish there were something updated for how IDEs use languages nowadays, in particular, walking through a good way to implement the language server protocol.

The calculator language that every compiler book starts with should be LSP-first.

A MOOC would be great, but I'd also be happy with a series of blog posts.

Does anyone know of good material bridging the gap between traditional compiler architecture and the LSP?

Re: Advanced Compilers: Self-Guided Online Course

#187

Post by specialist » Sat, Dec 12, 2020, 6:55 AM UTC

haberman wrote: post #168

morelisp wrote: post #128

Earlier quoted context omitted.

Packrat parsers are notably faster than recursive descent parsers (also critical for IDE use) and by turning them "inside out" (replacing their memoization with dynamic programming) you get a pika parser which has very good recovery ability. There are varying techniques to improve error recovery for all forms of parsing but hacked-up recursive descent (certainly the most common kind of parser I still write for my hac…

> Packrat parsers are notably faster than recursive descent parsers I think this needs to be qualified. I don't think a packrat parser is going to beat a deterministic top-down parser. Maybe the packrat parser will win if the recursive descent parser is backtracking.

u/morelisp may have meant faster to develop, not runtime performance.

Re: Advanced Compilers: Self-Guided Online Course

#188

Post by [deleted] » Sat, Dec 12, 2020, 7:22 AM UTC

kingaillas wrote: post #170

Kranar wrote: post #149

Earlier quoted context omitted.

Strictly speaking, D is not context free nor is any statically typed programming language. That said most languages, including D, have supersets that are context free and can be used to build an AST which can then be refined further with context sensitive checks (ie. variables are used after declaration) and then even further with type checks. Many language tools don't need a full blown language parser and can get by…

You realize the poster you are responding to is the creator of D? And has spend his career writing compilers? I'm not sure he needs to have someone explain what a context free grammar is.

[deleted]

Re: Advanced Compilers: Self-Guided Online Course

#189

Post by lifthrasiir » Sat, Dec 12, 2020, 7:36 AM UTC

onei wrote: post #152

ohazi wrote: post #127

Earlier quoted context omitted.

Your IDE parser will be unusable if it goes bananas while you're typing the characters needed to get from one fully, correctly parseable state to the next. It needs to be able to handle: printf("hello"); and also: prin and also: printf("He It also needs to be able to autocomplete function signatures that exist below the current line being edited, so the parser can't simply bail out as soon as it reaches the first inc…

Isn't that pretty standard for a parser? When was the last time a compiler bailed on the very first error it hit and refused to do anything else? The solution is to pick synchronisation points to start parsing again, i.e. ; at the end of a statement or } at the end of a block.

How can you be sure that that } is the end of a certain defined block? This most importantly affects the scoping and in many cases it's ambiguous. IDEs do have rich metadata besides from the source code but then parsers should be aware of them.

Re: Advanced Compilers: Self-Guided Online Course

#190

Post by Kranar » Sat, Dec 12, 2020, 7:43 AM UTC

kingaillas wrote: post #170

Kranar wrote: post #149

Earlier quoted context omitted.

Strictly speaking, D is not context free nor is any statically typed programming language. That said most languages, including D, have supersets that are context free and can be used to build an AST which can then be refined further with context sensitive checks (ie. variables are used after declaration) and then even further with type checks. Many language tools don't need a full blown language parser and can get by…

You realize the poster you are responding to is the creator of D? And has spend his career writing compilers? I'm not sure he needs to have someone explain what a context free grammar is.

I understand you wish to flatter WalterBright, but please note that your comment is fairly toxic and not well suited to Hacker News. Please stay on topic and feel free to contribute to the points being made. This kind of hero worship often just degrades discussion and is better left to other forms of social media.