8 ms·

A nice thing you get in return tho is for separate platforms you can disable code just in the language itself; it doesn't need to be a preprocessor or or handle

• dleslie 4y ago
  Uncommenting a line for a platform-specific feature isn't really any more difficult than decorating a function, adding a pre-processor gate, or any of the other normal ways of doing it.
  • dilap 4y ago
    more difficult maybe maybe not, but the way zig does it is simpler in that it's fewer languages you have to know: you don't have to learn the c preprocessor (c/c++) or about magic +build tags (Go) or whatever; it's just normal conditionals in the same language. you might [reasonably] say you can't care about that kind of simplicity, which is fine; but radical simplicity is definitely one of the major charms of zig. (and you don't use the zig feature by commenting/uncommenting, it's via inspection of the environment/flags in the comptime code.)
    • Kwpolska 4y ago
      So how does Zig handle platform-specific stuff that cannot be compiled on other platforms? Is it an `if` resolved at compile time causing the uncompileable code to be unused and disappear after the Zir stage? You don't need a full preprocessor with macros and other evil stuff. Just #define and #ifdef would solve this without allowing wrong code that randomly disappears. And learning and understanding these two directives requires zero mental effort.
      • TUSF 4y ago
        > Is it an `if` resolved at compile time causing the uncompileable code to be unused and disappear after the Zir stage? Yes. It's exactly that, because Zig very aggressively evaluates values that are known at compile time. It's as simple as: if (builtin.os.tag == .linux) { // Everything here only exists if compiling for Linux. } The standard library uses this quite a lot for OS/CPU specific things.
        • dleslie 4y ago
          That's elegant. It's also not so different than a preprocessor gate, or a function attribute.
          • Kwpolska 4y ago
            I don’t agree that it’s elegant. A preprocessor directive or a function attribute makes it more obvious that the code it covers may be valid only in some conditions. On the other hand, if the language optimizes some `if` statements out, you may have invalid code without noticing — and not only in the case of OS-specific code, but possibly also regular code whose `if` condition became a compile-time constant, even unintentionally/temporarily/by mistake.
            • wtetzner 4y ago
              I think it’s elegant, but it seems to me that the check shouldn’t be evaluated until after type checking. But I’m probably missing something about the way Zig works.
              • insanitybit 4y ago
                I think types are generated via const, so that wouldn't be possible.
              • anonymoushn 4y ago
                This won't work because the conditionally-compiled platform-specific code is expected to not typecheck (or to use fields that do not exist, etc.) The same feature is also used for specializing generic containers to specific types (an idea that became famous after the resounding success of std::vector<bool>) so that for example arraylists of u8 expose a Writer but arraylists of f64 do not. Most code that is conditional on T == u8 won't typecheck if T != u8. I guess more generally these features are used for implementing fmt, json encoders and decoders, etc. None of these thing would work if code conditional on the type had to typecheck for all types.
    • dleslie 4y ago
      If you're already concerned with, and developing, platform-specific code then the extra knowledge isn't really that hard to grasp. Moreover, I can grep for preprocessor defines, attributes, and such by name. There's no way to grep a project for code commented out to prevent execution on some platforms.
    • dontlaugh 4y ago
      It’s not necessarily simpler than an explicit hygienic macro system or similar, since comptime is a complex feature with surprising consequences. Mostly it moves the complexity around.
      • throwawaymaths 4y ago
        I work in a language with hygienic macros and in zig, and zigs way is simpler and more constrained.
• notduncansmith 4y ago
  It seems like a nice balance might be a compiler config that accepts a list of paths to unconditionally compile, so that users can enforce stricter checks in their own project without forcing authors of their dependencies to do the same.
  • lostmsu 4y ago
    > compiler config How is this better than a line in the language itself?
    • notduncansmith 4y ago
      Even better
  • throwawaymaths 4y ago
    Doesn't @refalldecls do this?
    • anonymoushn 4y ago
      This does it, but you might still find compile errors later than you'd like in comptime-heavy code.
      • throwawaymaths 4y ago
        It's the carrot to get you to write tests. You're writing tests, right?
• jay-barronville 4y ago
  > A nice thing you get in return tho is for separate platforms you can disable code just in the language itself; it doesn't need to be a preprocessor or or handled magically in the build system. I don’t know if I consider this a nice thing when thinking about it from a systems language lens. When working at the low level, I like the immediate clarity and compile-time feedback that preprocessor-like checks bring. They’re not perfect, but I think I prefer that instead of relying on laziness. > It's also not nearly as bad as a dynamically typed language: you might have broken code you won't realize until you try to use it, but you'll always realize at compile-time. This is correct, but to me, the elephant in the room here though is that this makes it much easier to introduce broken technical debt into a codebase. This likely means that when conducting large-scale refactors in a Zig codebase, as the amount of potentially broken code increases, the count of hair strands remaining in one’s scalp decreases. Zig is an awesome language, but frankly, I think compiler laziness like this is pretty odd for a statically-typed systems language and not the behavior one would intuitively expect.