Dear sir, you have built a compiler • Hacker News Board

Re: Dear sir, you have built a compiler

#41

Post by Karunamon » Thu, Jan 13, 2022, 3:27 PM UTC

jimmaswell wrote: post #38

hobofan wrote: post #31

I feel like you can apply the same sentiment to many of the "big scary things" in programming. Things that you don't want to build (as far as "common engineering wisdom" is to be believed): - a compiler - a programming language (not sure that there is a difference to compiler as stated in the article) - a database (query engine) - a CMS - a ERP But sometimes you actually _do_ want to build that (even if every alarm b…

Implementing a small domain-specific language is fairly easy. Why avoid it?

Because the complexity of the problem tends to scale to your willingness to address said complexity. In other words, it likely won't stay small for long if it gets any users, and now you're the maintainer for a tool used by others.

Re: Dear sir, you have built a compiler

#42

Post by choeger » Thu, Jan 13, 2022, 3:27 PM UTC

The language pattern occurs quite frequently in many domains. Unfortunately, I have so far only seen half-assed interpreters. At best, people did a shallow embedding (interpreter) of their DSL. No one ever did a true compiler.

I think the reason for this can be found in the ideal encoding of the input language: In its most concise formulation, a language is a recursive algebraic datatypes. Handling of that input requires a recursive algorithm that deals with all corner cases. Engineers I worked with tend to not see their input language as an ADT, though. They focus on some particular use cases and if there is a specification it is often too large and yet incomplete. But on top of that comes the hesitation to implement a complete algorithm. Nearly every time, some "corner case" is ignored because "nobody uses it" and we end up with an implementation that is factually incorrect and incomplete.

Re: Dear sir, you have built a compiler

#43

Post by hardwaregeek » Thu, Jan 13, 2022, 3:33 PM UTC

On the flip side, if you start out with "ah shoot I have to write a compiler", that can be paralyzing unless you happen to know how to write a compiler. Sometimes it's best to just write code, do it the wrong way, and then learn the compiler stuff on the fly.

Re: Dear sir, you have built a compiler

#44

Post by eatonphil » Thu, Jan 13, 2022, 3:35 PM UTC

It's a hilarious post but I'm scared and curious to ask what this is in response to?

Re: Dear sir, you have built a compiler

#45

Post by oshiar53-0 » Thu, Jan 13, 2022, 3:36 PM UTC

ot wrote: post #40

hobofan wrote: post #31

I feel like you can apply the same sentiment to many of the "big scary things" in programming. Things that you don't want to build (as far as "common engineering wisdom" is to be believed): - a compiler - a programming language (not sure that there is a difference to compiler as stated in the article) - a database (query engine) - a CMS - a ERP But sometimes you actually _do_ want to build that (even if every alarm b…

I would add encryption/authentication protocols to the list.

Make sure you don't roll your own crypto on your way, though.

Unless when it somehow becomes the absolute necessity...or it's for your dissertation.

Re: Dear sir, you have built a compiler

#46

Post by ianbicking » Thu, Jan 13, 2022, 3:36 PM UTC

sunir wrote: post #12

I think you should almost always build a compiler when presented with a parse then execute problem. It is so much faster to create a small machine that is fed data to specific the program, and a test harness that also drives that machine, then it is to hand code every little case repetitively. Or maybe I like building little compilers.

When you describe it that way it reminds me of SAX [1] – I always hated SAX, but eventually realized it was kind of a tokenizer that left it up to the developer to figure out how to turn that into a compiler, though in this case compiling XML input into some internal data structure or action.

[1] https://en.wikipedia.org/wiki/Simple_API_for_XML

Re: Dear sir, you have built a compiler

#47

Post by quotemstr » Thu, Jan 13, 2022, 3:37 PM UTC

TillE wrote: post #18

YAGNI is a good principle here. Whenever I've found myself thinking about reaching for a parser library, I was over-complicating or over-generalizing the problem. Write the code you need to solve the problem you actually have.

The article makes a good argument against YAGNI, at least YAGNI applied in its naive form. The point is that if you're going to make an embedded language, just do it the right way from the start instead of trying to cobble it together with YAGNI-inspired half-assed implementations that break in weird cases.

Re: Dear sir, you have built a compiler

#48

Post by Cthulhu_ » Thu, Jan 13, 2022, 3:37 PM UTC

hobofan wrote: post #31

I feel like you can apply the same sentiment to many of the "big scary things" in programming. Things that you don't want to build (as far as "common engineering wisdom" is to be believed): - a compiler - a programming language (not sure that there is a difference to compiler as stated in the article) - a database (query engine) - a CMS - a ERP But sometimes you actually _do_ want to build that (even if every alarm b…

I'm hit by this at the moment. I need to build something so that users can revert to a previous version of a record, but it's constrained to sqlite. I'm (re) building versioned document stores or temporal tables in various POCs now and I'm scared.

Re: Dear sir, you have built a compiler

#49

Post by therealcamino » Thu, Jan 13, 2022, 3:37 PM UTC

throwfaangus wrote: post #9

olivierduval wrote: post #3

I'm always surprised by the lack of "easy" parser/compiler toolkit for more or less complete DSL... It looks like there's only - either full blown programming language for IT guys - "natural language" AI toolkits (not really usable yet for just simple automation by users) - graphical language like State Machine or "no code", missing loops and requiring mouse and boxes However, most of the time, user simply need some…

Just use flex / bison?

I've always found ANTLR to be more intuitive and maintainable than the flex/bison combination. And the learning curve is gentler.

Re: Dear sir, you have built a compiler

#50

Post by mikewarot » Thu, Jan 13, 2022, 3:39 PM UTC

I wrote an inspection tracking system in Turbo Pascal/MS-DOS with some Norand hand-held computers running PL/N back in the late 1980s. As we modified the system to handle new classes of inspections, I ended up having a little configuration file that sat in the folder, that looked just like Pascal.

I encrypted that file by XORing it with a random string in a little command line program for the purpose. It also decrypted the file so you could work on it, of course.

Those were fun days, except for the lack of GIT, and the resultant stack of floppy disks I kept the source backed up on.