5 ms·

Yep, you are correct! The first example was a bit too simplistic. A better one would be https://github.com/RetroDev256/comptime_suffix_automaton https://github.

Yep, you are correct! The first example was a bit too simplistic. A better one would be https://github.com/RetroDev256/comptime_suffix_automaton https://github.com/RetroDev256/comptime_suffix_automaton Do note that your linked godbolt code actually demonstrates one of the two sub-par examples though.

uecker 1y ago
I haven't looked at the more complex example, but the second issue is not too difficult to fix: https://godbolt.org/z/48T44PvzK https://godbolt.org/z/48T44PvzK For complicated things, I haven't really understood the advantage compared to simply running a program at build time.
- Cloudef 1y ago
  To be honest your snippet isn't really C anymore by using a compiler builtin. I'm also annoyed by things like `foo(int N, const char x[N])` which compilation vary wildly between compilers (most ignore them, gcc will actually try to check if the invariants if they are compile time known) > I haven't really understood the advantage compared to simply running a program at build time. Since both comptime and runtime code can be mixed, this gives you a lot of safety and control. The comptime in zig emulates the target architecture, this makes things like cross-compilation simply work. For program that generates code, you have to run that generator on the system that's compiling and the generator program itself has to be aware the target it's generating code for.
  - uecker 1y ago
    It also works with memcpy from the library: https://godbolt.org/z/Mc6M9dK4M https://godbolt.org/z/Mc6M9dK4M I just didn't feel like burdening godbolt with an inlclude. I do not understand your criticism of [N]. This gives compiler more information and catches errors. This is a good thing! Who could be annoyed by this: https://godbolt.org/z/EeadKhrE8 https://godbolt.org/z/EeadKhrE8 (of course, nowadays you could also define a descent span type in C) The cross-compilation argument has some merit, but not enough to warrant the additional complexity IMHO. Compile-time computation will also have annoying limitations and makes programs more difficult to understand. I feel sorry for everybody who needs to maintain complex compile time code generation. Zig certainly does it better than C++ but still..
    - Cloudef 1y ago
      > I do not understand your criticism of [N]. This gives compiler more information and catches errors. This is a good thing! It only does sane thing in GCC, in other compilers it does nothing and since it's very underspec'd it's rarely used in any C projects. It's shame Dennis's fat pointers / slices proposal was not accepted. > warrant the additional complexity IMHO In zig case the comptime reduces complexity, because it is simply zig. It's used to implement generics, you can call zig code compile time, create and return types. This old talk from andrew really hammers in how zig is evolution of C: https://www.youtube.com/watch?v=Gv2I7qTux7g https://www.youtube.com/watch?v=Gv2I7qTux7g
      - uecker 1y ago
        Then the right thing would be to complain about those other compilers. I agree that Dennis' fat pointer proposal was good. Also in Zig it does not reduce complexity but adds to it by creating an distinction between compile time and run-time. It is only lower complexity by comparing to other implementations of generic which are even worse.
        Cloudef 1y ago
        Sure there's tradeoffs for everything, but if I had to choose between macros, templates, or zig's comptime, I'd take the comptime any time.
        uecker 1y ago
        To each their own, I guess. I still find C to be so much cleaner than all the languages that attempt to replace it, I can not possibly see any of them as a future language for me. And it turns out that it is possible to fix issues in C if one is patient enough. Nowadays I would write this with a span type: https://godbolt.org/z/nvqf6eoK7 https://godbolt.org/z/nvqf6eoK7 which is safe and gives good code. update: clang is even a bit nicer https://godbolt.org/z/b99s1rMzh https://godbolt.org/z/b99s1rMzh although both compile it to a constant if the other argument is known at compile time. In light of this, the Zig solution does not impress me much: https://godbolt.org/z/1dacacfzc https://godbolt.org/z/1dacacfzc

uecker 1y ago

I haven't looked at the more complex example, but the second issue is not too difficult to fix: https://godbolt.org/z/48T44PvzK https://godbolt.org/z/48T44PvzK For complicated things, I haven't really understood the advantage compared to simply running a program at build time.

Cloudef 1y ago
To be honest your snippet isn't really C anymore by using a compiler builtin. I'm also annoyed by things like `foo(int N, const char x[N])` which compilation vary wildly between compilers (most ignore them, gcc will actually try to check if the invariants if they are compile time known) > I haven't really understood the advantage compared to simply running a program at build time. Since both comptime and runtime code can be mixed, this gives you a lot of safety and control. The comptime in zig emulates the target architecture, this makes things like cross-compilation simply work. For program that generates code, you have to run that generator on the system that's compiling and the generator program itself has to be aware the target it's generating code for.
- uecker 1y ago
  It also works with memcpy from the library: https://godbolt.org/z/Mc6M9dK4M https://godbolt.org/z/Mc6M9dK4M I just didn't feel like burdening godbolt with an inlclude. I do not understand your criticism of [N]. This gives compiler more information and catches errors. This is a good thing! Who could be annoyed by this: https://godbolt.org/z/EeadKhrE8 https://godbolt.org/z/EeadKhrE8 (of course, nowadays you could also define a descent span type in C) The cross-compilation argument has some merit, but not enough to warrant the additional complexity IMHO. Compile-time computation will also have annoying limitations and makes programs more difficult to understand. I feel sorry for everybody who needs to maintain complex compile time code generation. Zig certainly does it better than C++ but still..
  - Cloudef 1y ago
    > I do not understand your criticism of [N]. This gives compiler more information and catches errors. This is a good thing! It only does sane thing in GCC, in other compilers it does nothing and since it's very underspec'd it's rarely used in any C projects. It's shame Dennis's fat pointers / slices proposal was not accepted. > warrant the additional complexity IMHO In zig case the comptime reduces complexity, because it is simply zig. It's used to implement generics, you can call zig code compile time, create and return types. This old talk from andrew really hammers in how zig is evolution of C: https://www.youtube.com/watch?v=Gv2I7qTux7g https://www.youtube.com/watch?v=Gv2I7qTux7g
    - uecker 1y ago
      Then the right thing would be to complain about those other compilers. I agree that Dennis' fat pointer proposal was good. Also in Zig it does not reduce complexity but adds to it by creating an distinction between compile time and run-time. It is only lower complexity by comparing to other implementations of generic which are even worse.
      - Cloudef 1y ago
        Sure there's tradeoffs for everything, but if I had to choose between macros, templates, or zig's comptime, I'd take the comptime any time.
        uecker 1y ago
        To each their own, I guess. I still find C to be so much cleaner than all the languages that attempt to replace it, I can not possibly see any of them as a future language for me. And it turns out that it is possible to fix issues in C if one is patient enough. Nowadays I would write this with a span type: https://godbolt.org/z/nvqf6eoK7 https://godbolt.org/z/nvqf6eoK7 which is safe and gives good code. update: clang is even a bit nicer https://godbolt.org/z/b99s1rMzh https://godbolt.org/z/b99s1rMzh although both compile it to a constant if the other argument is known at compile time. In light of this, the Zig solution does not impress me much: https://godbolt.org/z/1dacacfzc https://godbolt.org/z/1dacacfzc