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> However, most modern languages (C, C++, Python, Java, etc..) are not making it easy, The article shows how easy it is to declare a struct of arrays in Java:

> However, most modern languages (C, C++, Python, Java, etc..) are not making it easy, The article shows how easy it is to declare a struct of arrays in Java: You declare a struct (class). Inside it you declare arrays. Done.

beagle3 5y ago
It is easy to declare, but it is not easy to use: You can pass the whole thing, but if you want to pass a subset of it? just one element? When you want to extend it, you have to extend many individual arrays, etc. When you want to copy entry 17 to entry 50, you can't loop over the fields - you have to spell out every field.
- tom_mellior 5y ago
  A subset of an AntColony is another AntColony containing sub-arrays. One element of an AntColony is an Ant which you can instantiate with the data at the appropriate index from each array. I'm not trying to be difficult, I really don't see the problem with implementing these basic programming tasks. I agree that spelling out the fields can become tedious if you have a lot of structures of arrays or lots of fields per structure. A 100-line Python script can generate all this code for you if you prefer. Sure, it's a "limitation" of most programming languages that they don't provide this out of the box. But not a big limitation, I'd argue. Many languages even have features that allow you to write this functionality as a library, 100% inside the language (Python and Java annotations, for example).
  - beagle3 5y ago
    > I really don't see the problem with implementing these basic programming tasks. That you have to write them over and over again for every single class. You offer to do that with Python. > But not a big limitation, I'd argue. Many languages even have features that allow you to write this functionality as a library, 100% inside the language (Python and Java annotations, for example). This is an argument of the "all languages that are Turing complete are essentially equivalent" kind. True, but not interesting in this context. Ecosystem matters. If your Java program is the only one that does these things, it may just as well not be Java. You will be unable to use any other library without back-and-force adapters, for example.
    - tom_mellior 5y ago
      > That you have to write them over and over again for every single class. You offer to do that with Python. Or with some other code generator. A mythical language with SoA/AoS transformation "built in" will do exactly the same under the covers. But it might not offer other features you are used to, or (your argument) a sufficiently rich library ecosystem. You might as well do it yourself and use a language you are otherwise familiar and happy with. > This is an argument of the "all languages that are Turing complete are essentially equivalent" kind. Is it? You can't do what I described in C, for instance. To be clear, what I meant when I wrote "as a library, 100% inside the language" was that, given the appropriate definitions in a library, not in an external tool you run before your build, you just write something like the following Python: class Ant: someField = ... someOtherField = ... @StructureOfArrays class AntColony: pass or something the following Java: class Ant { int someField; boolean someOtherField; } @StructureOfArrays class AntColony { } and get all the features you can dream of generated for you inside the AntColony class, which you then use exactly as if you had typed things out yourself. You can't do this in C. This isn't an "all Turing complete languages" argument as far as I can see. > You will be unable to use any other library without back-and-force adapters, for example. I don't understand what you mean. In the above example, the Ant class exists, so you don't need adapters. The arrays inside the AntColony class exist (once the annotation processor is done with them), so you don't need adapters.
      - beagle3 5y ago
        > You might as well do it yourself and use a language you are otherwise familiar and happy with. Nim, Rust, D, Lisp support this already as compiled languages, without sacrificing anything - perhaps also Zig - at the macro level. Jai offers it as a language feature, but I don't think that's a particularly good idea - it's just that Jai tries to stay simple in such a way that doesn't let it be a user-level thing. > Is it? You can't do what I described in C, for instance. Not exactly, no, but you can with "X-macros", and I have - in fact - been doing that since 2005 or so, using only features from C89 ; I admit I have not used Java in the last 10 years, and then it was impossible - maybe some of the revisions in the last decade made it possible "inside the language" - what's the name of the feature I need to look up? > I don't understand what you mean. In the above example, the Ant class exists, so you don't need adapters. The arrays inside the AntColony class exist (once the annotation processor is done with them), so you don't need adapters. And now, you try to use the standard library "Sort" or "Find", it doesn't work without adapters, even if you have comparators defined for Ant -- and many other things that assume that objects are not part of a colony. It's hard to explain in a short post. I occasionally use a language called "K" of the APL family, which makes all of this incredibly trivial from the get go. It's not a new language - K itself IIRC predates Java by a couple of years, APL (of which K is often considered a dialect) was first specified in 1958 and implemented in 1962. It basically considers everything an array - one or multiple dimensional - and field access is nothing more than having one of the axes specified by symbols rather than numbers. This makes everything incredibly simple and uniform to an extent that is hard to describe to someone who has not experienced it. (And indeed, in the turing sense it makes no difference .... but if you implement your Java objects as "mapping from field to value" you may get some of the benefits but will not really be using Java or be able to use the ecosystem)
theamk 5y ago
The code you to actually use it is pretty dangerous - you need to keep the index and “main pointer” in separate variables, but always use them together. And indexes are all plain untyped integers, so no compiler will warn you if you use wrong index variable. And GC is no longer thing, so “write after free” and friends come back. Going to column arrays in high-level languages brings back many of the C bugs that we really hoped to forget.

beagle3 5y ago

It is easy to declare, but it is not easy to use: You can pass the whole thing, but if you want to pass a subset of it? just one element? When you want to extend it, you have to extend many individual arrays, etc. When you want to copy entry 17 to entry 50, you can't loop over the fields - you have to spell out every field.

tom_mellior 5y ago
A subset of an AntColony is another AntColony containing sub-arrays. One element of an AntColony is an Ant which you can instantiate with the data at the appropriate index from each array. I'm not trying to be difficult, I really don't see the problem with implementing these basic programming tasks. I agree that spelling out the fields can become tedious if you have a lot of structures of arrays or lots of fields per structure. A 100-line Python script can generate all this code for you if you prefer. Sure, it's a "limitation" of most programming languages that they don't provide this out of the box. But not a big limitation, I'd argue. Many languages even have features that allow you to write this functionality as a library, 100% inside the language (Python and Java annotations, for example).
- beagle3 5y ago
  > I really don't see the problem with implementing these basic programming tasks. That you have to write them over and over again for every single class. You offer to do that with Python. > But not a big limitation, I'd argue. Many languages even have features that allow you to write this functionality as a library, 100% inside the language (Python and Java annotations, for example). This is an argument of the "all languages that are Turing complete are essentially equivalent" kind. True, but not interesting in this context. Ecosystem matters. If your Java program is the only one that does these things, it may just as well not be Java. You will be unable to use any other library without back-and-force adapters, for example.
  - tom_mellior 5y ago
    > That you have to write them over and over again for every single class. You offer to do that with Python. Or with some other code generator. A mythical language with SoA/AoS transformation "built in" will do exactly the same under the covers. But it might not offer other features you are used to, or (your argument) a sufficiently rich library ecosystem. You might as well do it yourself and use a language you are otherwise familiar and happy with. > This is an argument of the "all languages that are Turing complete are essentially equivalent" kind. Is it? You can't do what I described in C, for instance. To be clear, what I meant when I wrote "as a library, 100% inside the language" was that, given the appropriate definitions in a library, not in an external tool you run before your build, you just write something like the following Python: class Ant: someField = ... someOtherField = ... @StructureOfArrays class AntColony: pass or something the following Java: class Ant { int someField; boolean someOtherField; } @StructureOfArrays class AntColony { } and get all the features you can dream of generated for you inside the AntColony class, which you then use exactly as if you had typed things out yourself. You can't do this in C. This isn't an "all Turing complete languages" argument as far as I can see. > You will be unable to use any other library without back-and-force adapters, for example. I don't understand what you mean. In the above example, the Ant class exists, so you don't need adapters. The arrays inside the AntColony class exist (once the annotation processor is done with them), so you don't need adapters.
    - beagle3 5y ago
      > You might as well do it yourself and use a language you are otherwise familiar and happy with. Nim, Rust, D, Lisp support this already as compiled languages, without sacrificing anything - perhaps also Zig - at the macro level. Jai offers it as a language feature, but I don't think that's a particularly good idea - it's just that Jai tries to stay simple in such a way that doesn't let it be a user-level thing. > Is it? You can't do what I described in C, for instance. Not exactly, no, but you can with "X-macros", and I have - in fact - been doing that since 2005 or so, using only features from C89 ; I admit I have not used Java in the last 10 years, and then it was impossible - maybe some of the revisions in the last decade made it possible "inside the language" - what's the name of the feature I need to look up? > I don't understand what you mean. In the above example, the Ant class exists, so you don't need adapters. The arrays inside the AntColony class exist (once the annotation processor is done with them), so you don't need adapters. And now, you try to use the standard library "Sort" or "Find", it doesn't work without adapters, even if you have comparators defined for Ant -- and many other things that assume that objects are not part of a colony. It's hard to explain in a short post. I occasionally use a language called "K" of the APL family, which makes all of this incredibly trivial from the get go. It's not a new language - K itself IIRC predates Java by a couple of years, APL (of which K is often considered a dialect) was first specified in 1958 and implemented in 1962. It basically considers everything an array - one or multiple dimensional - and field access is nothing more than having one of the axes specified by symbols rather than numbers. This makes everything incredibly simple and uniform to an extent that is hard to describe to someone who has not experienced it. (And indeed, in the turing sense it makes no difference .... but if you implement your Java objects as "mapping from field to value" you may get some of the benefits but will not really be using Java or be able to use the ecosystem)

theamk 5y ago

The code you to actually use it is pretty dangerous - you need to keep the index and “main pointer” in separate variables, but always use them together. And indexes are all plain untyped integers, so no compiler will warn you if you use wrong index variable. And GC is no longer thing, so “write after free” and friends come back. Going to column arrays in high-level languages brings back many of the C bugs that we really hoped to forget.