8 ms·

Most of the negatives are heavily focused on implementation rather than design, which I don't disagree with. However, the positives of targeting any language a

by Refefer 13y ago

Most of the negatives are heavily focused on implementation rather than design, which I don't disagree with. However, the positives of targeting any language at a stable byte code is incredibly valuable... such as an implementation of javascript itself. A bytecode approach provides a superset to our current status quo. That said, as browsers act more like operating systems, it makes me wonder if we've somewhat missed the point. I agree with you about starting from scratch. I think if history is any indication, ultimately we'll end up having to write a new 'web' with very different semantics and design philosophies; goodness knows the old metaphor is starting to creak in a number of problematic ways.

azakai 13y ago
> However, the positives of targeting any language at a stable byte code is incredibly valuable... such as an implementation of javascript itself. A bytecode approach provides a superset to our current status quo. Not necessarily, it depends which bytecode. For example the bytecode in PNaCl, which is based on LLVM IR, is excellent for C and related languages, but not for many other important languages. Worth reading this about the limitations of LLVM IR as a bytecode: http://lists.cs.uiuc.edu/pipermail/llvmdev/2011-October/043719.html http://lists.cs.uiuc.edu/pipermail/llvmdev/2011-October/0437... I've also written a post about the limitations of any single bytecode to achieve all the goals the web needs: http://mozakai.blogspot.com/2013/05/the-elusive-universal-web-bytecode.html http://mozakai.blogspot.com/2013/05/the-elusive-universal-we...
BrendanEich 13y ago
Java has a bytecode for its client embedding; so does Flash ActionScript. This led to trouble. From http://brendaneich.github.io/Strange-Loop-2012/#/27 http://brendaneich.github.io/Strange-Loop-2012/#/27, some pros for JS and cons for bytecode: * Dynamic typing ⇒ no verification * Type inference ⇒ delayed optimization * Would bytecode compress as well? * Bytecode standardization would suck * Bytecode versioning would suck more * Low-level bytecode is future-hostile Remember Java bytecode backward compatibility hampering language evolution, in the generics (erasure) debate and result. Then they broke bytecode compat anyway. Flash has two language implementations in it, one for AS2 and the other (Tamarin) for AS3. Only way to be sure about AS2 compat! In many ways, with JS you have one problem; add bytecode and now you have two.
- drdaeman 13y ago
  But asm.js is a bytecode, isn't it? Just with a clever-but-weird encoding that allows a backward compatibility. In a same manner, one can deliver, for example, an x86 bytecode in JS-encoded form. Just encode opcodes as, say, "eax = 1" instead of "\xB8\x01\0\0\0".
  - BrendanEich 13y ago
    No, asm.js is a JS subset. "bytecode" as boosted here would be a non-subset, like JVML to Java source. Sure, bits is bits. Doesn't matter if you're after gzipped good results. But bytecode hopes spring eternal and the hopers do not want gzipped, minified, Emscripten-produced asm.js. They want a different syntax.
    - drdaeman 13y ago
      > No, asm.js is a JS subset. "bytecode" as boosted here would be a non-subset, like JVML to Java source. Sorry for quoting Wikipedia, but bytecode is just a form of instruction set designed for efficient execution by a software interpreter. Maybe I'm mistaken on this, but from reading about asm.js I got an impression that asm.js-aware browsers use different approach to asm.js code and treat it more like a weirdly-encoded bytecode, not as an ordirary JS source. Or I'm misunderstanding things? If so, asm.js is a bytecode. Whenever there's a correspondence between it and other languages doesn't matter for determining if it's bytecode or not, it's another (useful, but not related to being bytecode) property. > They want a different syntax. I don't think syntax matters that much, it's mostly semantics. Probably.
      - Skinney 13y ago
        actually, asm.js is just javascript. Basically, Mozilla looked at what sort of javascript code that the different JIT's allready handle really well, and made a specification out of it. So even in Chrome, asm.js will run very efficiently. Mozilla figuered out a way to write javascript code that made type-information easy to extract, which again makes it easy to AOT-compile. For instance, the following code: function asmjs(i) { i = i|0; return (i + 1)|0; } is valid javascript, and you can easily write this in your own programs. The "|0" means that the variable will be converted to a integer, because it is specified in the javascript standard. As an optimization, you can use this as a type annotation, kind of like writing "int i = 0;" This is what asm.js is in a nutshell, and why it's so easy to implement a special compiler for it.

by Refefer 13y ago

azakai 13y ago

> However, the positives of targeting any language at a stable byte code is incredibly valuable... such as an implementation of javascript itself. A bytecode approach provides a superset to our current status quo. Not necessarily, it depends which bytecode. For example the bytecode in PNaCl, which is based on LLVM IR, is excellent for C and related languages, but not for many other important languages. Worth reading this about the limitations of LLVM IR as a bytecode: http://lists.cs.uiuc.edu/pipermail/llvmdev/2011-October/043719.html http://lists.cs.uiuc.edu/pipermail/llvmdev/2011-October/0437... I've also written a post about the limitations of any single bytecode to achieve all the goals the web needs: http://mozakai.blogspot.com/2013/05/the-elusive-universal-web-bytecode.html http://mozakai.blogspot.com/2013/05/the-elusive-universal-we...

BrendanEich 13y ago

Java has a bytecode for its client embedding; so does Flash ActionScript. This led to trouble. From http://brendaneich.github.io/Strange-Loop-2012/#/27 http://brendaneich.github.io/Strange-Loop-2012/#/27, some pros for JS and cons for bytecode: * Dynamic typing ⇒ no verification * Type inference ⇒ delayed optimization * Would bytecode compress as well? * Bytecode standardization would suck * Bytecode versioning would suck more * Low-level bytecode is future-hostile Remember Java bytecode backward compatibility hampering language evolution, in the generics (erasure) debate and result. Then they broke bytecode compat anyway. Flash has two language implementations in it, one for AS2 and the other (Tamarin) for AS3. Only way to be sure about AS2 compat! In many ways, with JS you have one problem; add bytecode and now you have two.

drdaeman 13y ago
But asm.js is a bytecode, isn't it? Just with a clever-but-weird encoding that allows a backward compatibility. In a same manner, one can deliver, for example, an x86 bytecode in JS-encoded form. Just encode opcodes as, say, "eax = 1" instead of "\xB8\x01\0\0\0".
- BrendanEich 13y ago
  No, asm.js is a JS subset. "bytecode" as boosted here would be a non-subset, like JVML to Java source. Sure, bits is bits. Doesn't matter if you're after gzipped good results. But bytecode hopes spring eternal and the hopers do not want gzipped, minified, Emscripten-produced asm.js. They want a different syntax.
  - drdaeman 13y ago
    > No, asm.js is a JS subset. "bytecode" as boosted here would be a non-subset, like JVML to Java source. Sorry for quoting Wikipedia, but bytecode is just a form of instruction set designed for efficient execution by a software interpreter. Maybe I'm mistaken on this, but from reading about asm.js I got an impression that asm.js-aware browsers use different approach to asm.js code and treat it more like a weirdly-encoded bytecode, not as an ordirary JS source. Or I'm misunderstanding things? If so, asm.js is a bytecode. Whenever there's a correspondence between it and other languages doesn't matter for determining if it's bytecode or not, it's another (useful, but not related to being bytecode) property. > They want a different syntax. I don't think syntax matters that much, it's mostly semantics. Probably.
    - Skinney 13y ago
      actually, asm.js is just javascript. Basically, Mozilla looked at what sort of javascript code that the different JIT's allready handle really well, and made a specification out of it. So even in Chrome, asm.js will run very efficiently. Mozilla figuered out a way to write javascript code that made type-information easy to extract, which again makes it easy to AOT-compile. For instance, the following code: function asmjs(i) { i = i|0; return (i + 1)|0; } is valid javascript, and you can easily write this in your own programs. The "|0" means that the variable will be converted to a integer, because it is specified in the javascript standard. As an optimization, you can use this as a type annotation, kind of like writing "int i = 0;" This is what asm.js is in a nutshell, and why it's so easy to implement a special compiler for it.