6 ms·

We nailed it with arrays (Jan Knepper’s idea), the basic template design, compile-time function execution (CTFE) One of my favourite things about D is

• gmfawcett 10y ago
  I agree! But the compile-time interpreter isn't really "full". For example, you can't do arbitrary I/O in a compile-time expression (by design). Non-portable casts and inline ASM are other exceptions. See [1] for the full story. [1]: https://dlang.org/spec/function.html#interpretation https://dlang.org/spec/function.html#interpretation
  • Shoop 10y ago
    If inline asm or non-portable casts were allowed, D programs would compile inconsistently on different architectures. Compile time IO doesn't make much sense either. Not all limitations are shortcomings.
    • steveklabnik 10y ago
      > Compile time IO doesn't make much sense either. While I agree with D's decision here, there are other languages which do allow anything at compile time. See Jai, for example.
      • wtetzner 10y ago
        And Common Lisp, and Scheme, and Elixir, and Clojure, and I'm sure I'm missing a bunch :)
        • p0nce 10y ago
          Those come with the whole compiler at runtime.
        • lomnakkus 10y ago
          Even... Haskell! Dundundun! (I'm referring to Template Haskell.) As it turns out (IME) referencing arbitrary data (such as a database schema queried from a 'live' database) is actually of quite limited value. Where I actually agree that it makes sense is the 'read-a-checked-in-file-and-generate-code-at-compile-time-from-that'. Otherwise, you're mostly just looking at a lot of pain compared to just generating code (that you might check in).
    • Zardoz84 10y ago
      Compile time read have sense. For example, reading a XML to build a GUI on complete time instead on runtime (I see you GTK builder). Actually you can do this on CTFE on D, doing an import of a file and dumping it to an enum. The only big pitfall of this, is that enforces to read the whole file by the compiler.
      • Shoop 10y ago
        I withdraw my claim that compile time IO doesn't make any sense, but it is something I would be worried about. I wouldn't want the executable my build process produces to be changed by what files are laying around on the disk. Mixing in all of the state in the file system with something you want to be mostly stateless (your build process) seems like a dangerous idea to me.
        • dansze 10y ago
          The compiler already depends on the state of the file system though, notably because it depends on the source code. In the above case, the xml is essentially just another source file that happens to not be in the same language. An important difference is that the compiler doesn't know it's using that file ahead of time, which could have some unforeseen consequences, but I don't see anything immediately worrying about that fact since the compiler didn't know about the source either at it's own compile time.
        • duaneb 10y ago
          How is it any different from, say, a makefile?
      • p0nce 10y ago
        > reading a XML to build a GUI on complete time instead on runtime It can be done with: void[] ctData = import("file.xml"); For example, this feature is used in vibe.d to compile an HTML template language into more optimized code.
      • stcredzero 10y ago
        Compile time read have sense. Considering what we've known about the typical behavior of production programs for decades, why isn't there also an "Initialization Time" in addition to Compile Time and "runtime." (Steady State Time?)
• lucian1900 10y ago
  > D is a great, modern, safe language It's very nice, but it isn't memory safe.
  • posterboy 10y ago
    I wonder, could a portable ownership model be implemented with the templates?
    • steveklabnik 10y ago
      I thought there was a DIP for this, but cannot seem to find it now.
    • pcwalton 10y ago
      Not soundly, no. The borrow check requires flow-sensitive analysis. The lifetime typechecker requires subtyping-aware extensions to Hindley-Milner.
      • nialv7 10y ago
        Can you going into some details about this? Like proofs?
  • Shoop 10y ago
    When is D not memory safe?
    • steveklabnik 10y ago
      It has been years since I have actively programed in D, so take this with a grain of salt, but my understanding is that D only guarantees memory safety in its @safe subset. See here: https://dlang.org/spec/memory-safe-d.html https://dlang.org/spec/memory-safe-d.html Context: safe Rust is also a subset of unsafe Rust. But when people mention a language without qualifiers, they mean whatever the default is. D (appears) to default to a non-memory safe language, and Rust defaults to a memory-safe one. I believe this is what OP meant. (this also ignores the relative feature sets of the various sub/super-sets)
• pcwalton 10y ago
  > It's a bit sad that Rust is getting all of the attention in the spotlight This isn't a zero-sum game! D is a fine language.
  • jordigh 10y ago
    There is a limited resource here, which is programmers' time and attention. If everyone is scrambling to Rust, they will probably not give D as much attention. Without attention, D will probably not have a healthy collection of 3rd party libraries and tools.
    • lifthrasiir 10y ago
      I think D have been already given tons of attention, especially in its early years (just like other newer languages). That early-day reception defines the acceptance in, say, next decade---at which Rust has been relatively excelled than D, IMHO.
• justin66 10y ago
  To someone with only a passing interest, but a real interest nonetheless, D's position in the spotlight is a lot more comfortable than what's going on with rust. After a while, the way every thread about c, c++, systems programming, or operating systems draws the same predictable rust comments feels like being assaulted by a lunatic wielding a cheese grater.
  • santaclaus 10y ago
    I've seen this phenomenon called 'Rustwins law' as it bears striking similarities to Godwin's law in its inevitability.
    • stcredzero 10y ago
      If the law suggests that Rust wins, I'm sure the Rust community will not strenuously object.
      • notriddle 10y ago
        If it's going to match Godwin's Law, then whoever mentions Rust automatically loses the argument...
        • jordigh 10y ago
          Godwin's law isn't about losing the argument. It's just an observation that national socialism is going to be mentioned in the limit as the conversation grows without end.