8 ms·

Prep: Golang Comptime

106 points by Seb-C 2y ago

andyferris 2y ago
The cool thing that zig comptime does is that it interacts with the type system. This seems geared around computations, more than e.g. defining structs.
pa7ch 2y ago
I wonder what Go would look like if it had generics removed but something like comptime added.
- fjasdddwsfasd 2y ago
  I always felt like if and when Go chose to implement Generics it would be like what Zig did today.
  - deleted 2y ago
    [deleted]
- lenkite 2y ago
  comptime really should have been the approach to Generics taken by Golang instead of trying to blindly follow Java/C++ . It would have also fit into Go's philosophy of keeping it standard and simple - no separate mini language for generics . Wish the language designers had looked at Zig before rolling out generics.
  - pjmlp 2y ago
    Actually the way they were introduced, they are following up CLU from 1976!
Groxx 2y ago
TIL `go build -toolexec`. That... seems like it'd enable a lot of interesting shenanigans... I'm somewhat surprised by how little I see online about it.
SPascareli13 2y ago
I was thinking about that just the other day, who it would be really cool if Go had compile time code execution. I think Jai is making that a very prominent feature of the language.
- latenightcoding 2y ago
  re: Jai. I have never seen a language that is not even available get so much love and benefit of doubt.
  - whateveracct 2y ago
    cult of personality
    - jonathrg 2y ago
      That's pretty much it. Jonathan Blow's strongly worded negative opinions on most things attracts a certain kind of person who will go on to evangelize.
  - SPascareli13 2y ago
    I don't know if there's ever been a language that was announced 10 years before its first closed beta. I don't even know if having a "closed beta" for a language is something that really happens. So there's a lot that is different with Jai, it's more like a highly anticipated game than a language.
- lenkite 2y ago
  Isn't Jai still vapourware after a decade ? How does one even get the compiler and build programs ?
  - SPascareli13 2y ago
    > Isn't Jai still vapourware after a decade ? Yes, I guess. I wouldn't be surprised to see "Jai inspired" languages coming out before Jai itself, since some of the ideas look pretty good. > How does one even get the compiler and build programs ? Don't know how seriously you're asking this, but I believe you can apply to use it and if Jon likes your credentials and what you want to try it on he might let you have the compiler for some version. Don't know why he won't just open source it and say it's a early version passive of change, but game development is not usually very open source friendly compared to web dev.
binwiederhier 2y ago
Fascinating. There are some other interesting repos from the same author, namely https://github.com/pijng/goinject https://github.com/pijng/goinject, which lets you inject code as part of preprocessing. Feels a lot like Java’s annotation magic. Thanks for sharing. I wasn’t even aware Go had pre-processors, or that modifying the AST like that is even possible.
sammy2255 2y ago
[flagged]
tzury 2y ago
In an older project I have had a code file generated with constants to get same results. That is nice. Makes coding and build flow simple, clean and easier to maintain.
chriscbr 2y ago
Neat concept. I had a similar idea a few months ago about whether it's possible to achieve some form of comptime with TypeScript. I didn't get too far unfortunately, but I think the implementation would need to interact with the TypeScript compiler API in some way.
sammy2255 2y ago
[flagged]
- sammy2255 2y ago
  Cheers for the downvotes but it’s true
sluongng 2y ago
This is just integrated codegen into the build tool, right? Datadog has a similar project here https://github.com/DataDog/orchestrion https://github.com/DataDog/orchestrion that does the same thing. I think this kind of code gen is very wonky, and hard to debug unless there is some official API support for it. Using a sufficiently advanced build tool to handle this in a separate build step would help as well. But that usually causes problems with IDE support.
- jakewins 2y ago
  Yeah, this reminds me a lot of similar practices in the JVM world with compile time annotation processors. Bugs in those systems are hell to trace. Coming to the Go world of “if you’re gonna do code generation, write a dumb program that generates source code text, run it and check the result into source control” was a revelation - yeah, it’s ugly, but guess what? It can be debugged by human beings.
  - elcritch 2y ago
    It depends more on whether the language tooling supports it. I used Lombok back in the day with Netbeans. When properly setup it would pop to the generated code when debugging or if you went to a definition, pretty easy.
gwd 2y ago
Adding "-a" is probably going to slow down your compile times by quite a bit. If I were going to use something like this, I'd try to ensure the results only depended on things in the same file. I wonder if there's a way for `prep` to warn when the result depends on something outside the file. If there were language support for this sort of thing, it could track the dependencies itself.
mst 2y ago
I'd been looking at https://github.com/cosmos72/gomacro/ https://github.com/cosmos72/gomacro/ on and off to get similar functionality. (and by "looking at" I mean "kept meaning to try it but totally haven't got round to it yet" but I still think it's worth a look)
bsaul 2y ago
I don’t know if zig is going to become mainstream, but comptime is such a brilliant yet simple idea (the best ones) that it’s already written its name in the hallmark of programming languages.
syngrog66 2y ago
Other than a traditional compiler use case and stage, "codegen" is an obvious anti-pattern both for security and for a maintainer's complexity burden, and thus to be avoided. Just say no, kids. Life will be better.
eximius 2y ago
If I need to do compile-time pre-computation, I'd probably do it using "code generation" using something like this: https://github.com/linzhp/codegen_example/tree/master https://github.com/linzhp/codegen_example/tree/master * integrated into bazel rather than go-compiler-hacking * your "normal" code just imports the result - which can be go-to-definition-ed to see the generated code

106 points by Seb-C 2y ago

The cool thing that zig comptime does is that it interacts with the type system. This seems geared around computations, more than e.g. defining structs.

pa7ch 2y ago

I wonder what Go would look like if it had generics removed but something like comptime added.

fjasdddwsfasd 2y ago
I always felt like if and when Go chose to implement Generics it would be like what Zig did today.
- deleted 2y ago
  [deleted]
lenkite 2y ago
comptime really should have been the approach to Generics taken by Golang instead of trying to blindly follow Java/C++ . It would have also fit into Go's philosophy of keeping it standard and simple - no separate mini language for generics . Wish the language designers had looked at Zig before rolling out generics.
- pjmlp 2y ago
  Actually the way they were introduced, they are following up CLU from 1976!

Groxx 2y ago

TIL `go build -toolexec`. That... seems like it'd enable a lot of interesting shenanigans... I'm somewhat surprised by how little I see online about it.

SPascareli13 2y ago

I was thinking about that just the other day, who it would be really cool if Go had compile time code execution. I think Jai is making that a very prominent feature of the language.

latenightcoding 2y ago
re: Jai. I have never seen a language that is not even available get so much love and benefit of doubt.
- whateveracct 2y ago
  cult of personality
  - jonathrg 2y ago
    That's pretty much it. Jonathan Blow's strongly worded negative opinions on most things attracts a certain kind of person who will go on to evangelize.
- SPascareli13 2y ago
  I don't know if there's ever been a language that was announced 10 years before its first closed beta. I don't even know if having a "closed beta" for a language is something that really happens. So there's a lot that is different with Jai, it's more like a highly anticipated game than a language.
lenkite 2y ago
Isn't Jai still vapourware after a decade ? How does one even get the compiler and build programs ?
- SPascareli13 2y ago
  > Isn't Jai still vapourware after a decade ? Yes, I guess. I wouldn't be surprised to see "Jai inspired" languages coming out before Jai itself, since some of the ideas look pretty good. > How does one even get the compiler and build programs ? Don't know how seriously you're asking this, but I believe you can apply to use it and if Jon likes your credentials and what you want to try it on he might let you have the compiler for some version. Don't know why he won't just open source it and say it's a early version passive of change, but game development is not usually very open source friendly compared to web dev.

binwiederhier 2y ago

Fascinating. There are some other interesting repos from the same author, namely https://github.com/pijng/goinject https://github.com/pijng/goinject, which lets you inject code as part of preprocessing. Feels a lot like Java’s annotation magic. Thanks for sharing. I wasn’t even aware Go had pre-processors, or that modifying the AST like that is even possible.

sammy2255 2y ago

[flagged]

tzury 2y ago

In an older project I have had a code file generated with constants to get same results. That is nice. Makes coding and build flow simple, clean and easier to maintain.

chriscbr 2y ago

Neat concept. I had a similar idea a few months ago about whether it's possible to achieve some form of comptime with TypeScript. I didn't get too far unfortunately, but I think the implementation would need to interact with the TypeScript compiler API in some way.

sammy2255 2y ago

[flagged]

sammy2255 2y ago
Cheers for the downvotes but it’s true

sluongng 2y ago

This is just integrated codegen into the build tool, right? Datadog has a similar project here https://github.com/DataDog/orchestrion https://github.com/DataDog/orchestrion that does the same thing. I think this kind of code gen is very wonky, and hard to debug unless there is some official API support for it. Using a sufficiently advanced build tool to handle this in a separate build step would help as well. But that usually causes problems with IDE support.

jakewins 2y ago
Yeah, this reminds me a lot of similar practices in the JVM world with compile time annotation processors. Bugs in those systems are hell to trace. Coming to the Go world of “if you’re gonna do code generation, write a dumb program that generates source code text, run it and check the result into source control” was a revelation - yeah, it’s ugly, but guess what? It can be debugged by human beings.
- elcritch 2y ago
  It depends more on whether the language tooling supports it. I used Lombok back in the day with Netbeans. When properly setup it would pop to the generated code when debugging or if you went to a definition, pretty easy.

gwd 2y ago

Adding "-a" is probably going to slow down your compile times by quite a bit. If I were going to use something like this, I'd try to ensure the results only depended on things in the same file. I wonder if there's a way for `prep` to warn when the result depends on something outside the file. If there were language support for this sort of thing, it could track the dependencies itself.

mst 2y ago

I'd been looking at https://github.com/cosmos72/gomacro/ https://github.com/cosmos72/gomacro/ on and off to get similar functionality. (and by "looking at" I mean "kept meaning to try it but totally haven't got round to it yet" but I still think it's worth a look)

bsaul 2y ago

I don’t know if zig is going to become mainstream, but comptime is such a brilliant yet simple idea (the best ones) that it’s already written its name in the hallmark of programming languages.

syngrog66 2y ago

Other than a traditional compiler use case and stage, "codegen" is an obvious anti-pattern both for security and for a maintainer's complexity burden, and thus to be avoided. Just say no, kids. Life will be better.

eximius 2y ago

If I need to do compile-time pre-computation, I'd probably do it using "code generation" using something like this: https://github.com/linzhp/codegen_example/tree/master https://github.com/linzhp/codegen_example/tree/master * integrated into bazel rather than go-compiler-hacking * your "normal" code just imports the result - which can be go-to-definition-ed to see the generated code