4 ms·

Can you show a proof for that claim? I believe it to be nonsense.

bratsche 13y ago
I'm not sure if this is what the previous poster was talking about, but clang has some APIs that let you get access to the AST pretty easily. It's been a really long time since I've looked at it, and at the time I don't think it was exposed as a library API for general consumption. But for example: https://github.com/bratsche/clang/blob/gtkrewriter/tools/clang-cc/RewriteGtk.cpp https://github.com/bratsche/clang/blob/gtkrewriter/tools/cla...
- pat_punnu 13y ago
  What is his definition of better? It sounds like he thinks it's entirely objective, so he should be able to express it clearly and logically. Does he think that it's technically more powerful? Again he should be able to prove that if that's the case. Otherwise he's just giving a shitty opinion, and should say that. I think the claim is nonsense because with inline assembler there is nothing that you cannot express in C that you can with LLVM. So the decision between the two is opinion.
  - bratsche 13y ago
    I don't know what his definition of anything is. I happen to agree with you. The example I pasted above was just from my only experience working with a C AST. In that case I wanted to input C code and then write out a transformed version of it.
  - coldtea 13y ago
    >Does he think that it's technically more powerful? Again he should be able to prove that if that's the case. Otherwise he's just giving a shitty opinion, and should say that. It's not like it's some controversial opinion what he said -- it's both self evident and common place. It's you who offers the more controversial opinion (and in a rude way, to top). >I think the claim is nonsense because with inline assembler there is nothing that you cannot express in C that you can with LLVM. So the decision between the two is opinion. It's not about "expression", and nobody argued that you can express more in LLVM. This is missing the point by miles! It's about having more structure and less of an ad-hoc pipeline, which helps with better tooling, error prevention, etc. (Not only what you wrote is wrong, but even if the original argument was about expression, your opinion would still be wrong. Two things offering equivalent expressive power, does not mean that they are just as good to use in practice at all. Might as well ask "why invent new languages, when assembly can express everything"). The only benefit to using C for something like this is portability, which is something else altogether.
    - vidarh 13y ago
      > It's not like it's some controversial opinion what he said -- it's both self evident and common place. As someone who has written more than one compiler, I don't see how it is self-evident at all. It's also not at all that common-place compared to generating C or asm output textually. > It's about having more structure and less of an ad-hoc pipeline, which helps with better tooling, error prevention, etc. Those provide some benefits, sure. At the cost of massive amounts of complexity in the case of LLVM. > The only benefit to using C for something like this is portability, which is something else altogether. Now it is you who are wrong. Other people have already pointed out, for example, that C provides an easy-to-read intermediate format, and is simple to generate, as other benefits. Not having to deal with a massive C++ codebase is another. You may disagree that these other benefits are worth it, but for me at least they are (just taking a break from a compiler that generates textual asm because I find even that preferable to dealing with LLVM).
      - coldtea 13y ago
        Sure, I agree about this: "C provides an easy-to-read intermediate format, and is simple to generate, as other benefits. Not having to deal with a massive C++ codebase is another.". So portability and less dependencies, plus easier.
coldtea 13y ago
Nonsense?! Outputting text to be interpreted as code is far more low level and error prone than targeting an AST via an API like LLVMs. And you loose a lot of high quality tooling that you could take advantage of.
- pat_punnu 13y ago
  "more ... error prone" Can you prove that? If not, it's just a baseless opinion.
  - abraininavat 13y ago
    Can you prove that? If not, it's just a baseless opinion. You are wrong here. Unproved statements are not necessarily baseless opinions. They may be well supported opinions. I think you meant to ask him, "Can you support that?"
  - coldtea 13y ago
    What's with this childish "can you prove this, can you prove that" thing? Are you 12 year old? Not everything can (or should) be proved of the drop of a hat in a discussion list -- that doesn't make everything without a formal proof "baseless" opinion. If you cannot see the self-evidentness (sic) of a STRUCTURED API to produce an AST makes it easier to avoid mistakes compared to spitting out text to compile as a C program, then I'm not sure any proof would help anyway. It's like asking me to prove why using an XML processor to crete and save a DOM tree would produce more error free results than manually compiling tags as strings. Or why parsing a JSON file and working on the nodes is less error prone than using regular expressions to extract values from the JSON as a big string.
    - pat_punnu 13y ago
      We work in a technical field. We call ourselves engineers. The academic version is computer SCIENCE. Unsupportable opinions and opinions presented as facts are inexcusable.
      - 13y ago

I'm not sure if this is what the previous poster was talking about, but clang has some APIs that let you get access to the AST pretty easily. It's been a really long time since I've looked at it, and at the time I don't think it was exposed as a library API for general consumption. But for example: https://github.com/bratsche/clang/blob/gtkrewriter/tools/clang-cc/RewriteGtk.cpp https://github.com/bratsche/clang/blob/gtkrewriter/tools/cla...

pat_punnu 13y ago
What is his definition of better? It sounds like he thinks it's entirely objective, so he should be able to express it clearly and logically. Does he think that it's technically more powerful? Again he should be able to prove that if that's the case. Otherwise he's just giving a shitty opinion, and should say that. I think the claim is nonsense because with inline assembler there is nothing that you cannot express in C that you can with LLVM. So the decision between the two is opinion.
- bratsche 13y ago
  I don't know what his definition of anything is. I happen to agree with you. The example I pasted above was just from my only experience working with a C AST. In that case I wanted to input C code and then write out a transformed version of it.
- coldtea 13y ago
  >Does he think that it's technically more powerful? Again he should be able to prove that if that's the case. Otherwise he's just giving a shitty opinion, and should say that. It's not like it's some controversial opinion what he said -- it's both self evident and common place. It's you who offers the more controversial opinion (and in a rude way, to top). >I think the claim is nonsense because with inline assembler there is nothing that you cannot express in C that you can with LLVM. So the decision between the two is opinion. It's not about "expression", and nobody argued that you can express more in LLVM. This is missing the point by miles! It's about having more structure and less of an ad-hoc pipeline, which helps with better tooling, error prevention, etc. (Not only what you wrote is wrong, but even if the original argument was about expression, your opinion would still be wrong. Two things offering equivalent expressive power, does not mean that they are just as good to use in practice at all. Might as well ask "why invent new languages, when assembly can express everything"). The only benefit to using C for something like this is portability, which is something else altogether.
  - vidarh 13y ago
    > It's not like it's some controversial opinion what he said -- it's both self evident and common place. As someone who has written more than one compiler, I don't see how it is self-evident at all. It's also not at all that common-place compared to generating C or asm output textually. > It's about having more structure and less of an ad-hoc pipeline, which helps with better tooling, error prevention, etc. Those provide some benefits, sure. At the cost of massive amounts of complexity in the case of LLVM. > The only benefit to using C for something like this is portability, which is something else altogether. Now it is you who are wrong. Other people have already pointed out, for example, that C provides an easy-to-read intermediate format, and is simple to generate, as other benefits. Not having to deal with a massive C++ codebase is another. You may disagree that these other benefits are worth it, but for me at least they are (just taking a break from a compiler that generates textual asm because I find even that preferable to dealing with LLVM).
    - coldtea 13y ago
      Sure, I agree about this: "C provides an easy-to-read intermediate format, and is simple to generate, as other benefits. Not having to deal with a massive C++ codebase is another.". So portability and less dependencies, plus easier.

coldtea 13y ago

Nonsense?! Outputting text to be interpreted as code is far more low level and error prone than targeting an AST via an API like LLVMs. And you loose a lot of high quality tooling that you could take advantage of.

pat_punnu 13y ago
"more ... error prone" Can you prove that? If not, it's just a baseless opinion.
- abraininavat 13y ago
  Can you prove that? If not, it's just a baseless opinion. You are wrong here. Unproved statements are not necessarily baseless opinions. They may be well supported opinions. I think you meant to ask him, "Can you support that?"
- coldtea 13y ago
  What's with this childish "can you prove this, can you prove that" thing? Are you 12 year old? Not everything can (or should) be proved of the drop of a hat in a discussion list -- that doesn't make everything without a formal proof "baseless" opinion. If you cannot see the self-evidentness (sic) of a STRUCTURED API to produce an AST makes it easier to avoid mistakes compared to spitting out text to compile as a C program, then I'm not sure any proof would help anyway. It's like asking me to prove why using an XML processor to crete and save a DOM tree would produce more error free results than manually compiling tags as strings. Or why parsing a JSON file and working on the nodes is less error prone than using regular expressions to extract values from the JSON as a big string.
  - pat_punnu 13y ago
    We work in a technical field. We call ourselves engineers. The academic version is computer SCIENCE. Unsupportable opinions and opinions presented as facts are inexcusable.
    - 13y ago