WebAssembly
| Paradigm | Expression-oriented |
|---|---|
| Typing discipline | Static |
| Platform | Platform independent |
| License | Apache License |
| Filename extensions | .wast, .wasm |
| Website | webassembly |
| Influenced by | |
| asm.js, PNaCl | |
WebAssembly or wasm is an experimental efficient low-level programming language for in-browser client-side scripting, which is currently in development. Its initial aim is to support compilation from C and C++,[1] though other source languages such as Rust are also supported.[2]
Design[edit]
WebAssembly is a portable stack machine[3] which is designed to be faster to parse than JavaScript, as well as faster to execute.[1]
History[edit]
WebAssembly was first announced on 17 June 2015[4] and on 15 March 2016 was demonstrated executing Unity's Angry Bots in Firefox,[5] Chromium, Google Chrome,[6] and Microsoft Edge.[7]
Development[edit]
The initial implementation of WebAssembly support in browsers will be based on asm.js[8] and PNaCl.[9] After the minimum viable product (MVP) release, there are plans to support garbage collection[10] which would make WebAssembly a compilation target for garbage collected programming languages like Java and C#. The team working on WebAssembly includes people from Mozilla, Microsoft, Google and Apple.[9]
Representation[edit]
It is still early days and the standard is still in flux. However a minimum viable product has been defined ( https://github.com/WebAssembly/design/blob/master/MVP.md ).
It defines a WebAssembly binary format in human unfriendly binary format, as well as a slightly more human friendly "Linear Assembly Bytecode" format that looks like more traditional assembly languages.
The table below represents 3 different views of the same source code input from the left, as it is converted to a wasm intermediate format, then to wasm binary.
| C (Input Source) | text "linear assembly bytecode" (Intermediate Representation) | WASM binary encoding (Binary shown below in Hexidecimal) |
|---|---|---|
int factorial(int n) {
if (n == 0)
return 1;
else
return n * fac(n-1);
}
|
get_local 0
i64.const 0
i64.eq
if i64
i64.const 1
else
get_local 0
get_local 0
i64.const 1
i64.sub
call 0
i64.mul
end
|
20 00
42 00
51
04 7e
42 01
05
20 00
20 00
42 01
7d
10 00
7e
0b
|
(Source for above example in https://github.com/WebAssembly/design/blob/master/TextFormat.md )
Internally at the moment the tooling of the wasm compiler system uses S-Expressions (For parsing simplicity as well as extra information that "linear assembly bytecode" representation does not contain) to handle intermediate code. An example is shown below:
(module
(memory 256 256)
(export "memory" memory)
(type $FUNCSIG$dd (func (param f64) (result f64)))
(import $exp "global.Math" "exp" (param f64) (result f64))
(export "doubleExp" $doubleExp)
(func $doubleExp (param $0 f64) (result f64)
(f64.mul
(call_import $exp
(get_local $0)
)
(f64.const 2)
)
)
)
(Source for above in http://cultureofdevelopment.com/blog/build-your-first-thing-with-web-assembly/ )
See also[edit]
References[edit]
- ^ a b "WebAssembly High-Level Goals". GitHub / WebAssembly / design. 11 December 2015.
- ^ "Announcing Rust 1.14". The Rust Programming Language Blog. 22 December 2016.
- ^ "Design Rationale". GitHub / WebAssembly / design. 1 October 2016.
- ^ "Launch bug". GitHub / WebAssembly / design. 11 June 2015.
- ^ Wagner, Luke (14 March 2016). "A WebAssembly Milestone: Experimental Support in Multiple Browsers". Mozilla Hacks.
- ^ Thompson, Seth (15 March 2016). "Experimental support for WebAssembly in V8". V8 Blog.
- ^ Zhu, Limin (15 March 2016). "Previewing WebAssembly experiments in Microsoft Edge". Microsoft Edge dev blog.
- ^ "WebAssembly: a binary format for the web". ②ality – JavaScript and more. 18 June 2015.
- ^ a b Bright, Peter (18 June 2015). "The Web is getting its bytecode: WebAssembly". Ars Technica. Condé Nast.
- ^ "WebAssembly/design". GitHub. Retrieved 28 December 2015.
