Pros of Wasmtime

• Practical implementation of WebAssembly runtime
• Actively developed with frequent updates and new features
• Provides a CLI tool for running and debugging WebAssembly modules

Cons of Wasmtime

• More complex codebase due to its full runtime implementation
• May deviate from the spec in some edge cases or optimizations
• Requires more system resources to run compared to the spec

Code Comparison

Spec (abstract):

(module
  (func $add (param $a i32) (param $b i32) (result i32)
    local.get $a
    local.get $b
    i32.add))

Wasmtime (Rust implementation):

fn add(a: i32, b: i32) -> i32 {
    a + b
}

#[no_mangle]
pub extern "C" fn add_wrapper(a: i32, b: i32) -> i32 {
    add(a, b)
}

Summary

The WebAssembly spec repository defines the standard for WebAssembly, providing a reference implementation and test suite. Wasmtime, on the other hand, is a practical WebAssembly runtime that implements the spec. While the spec focuses on defining the language and its behavior, Wasmtime provides a usable runtime environment for executing WebAssembly modules. The spec uses abstract notation, while Wasmtime implements the functionality in Rust, making it more concrete but also more complex.

Pros of Emscripten

• Provides a complete toolchain for compiling C/C++ to WebAssembly
• Offers a wide range of APIs and libraries for web integration
• Actively maintained with frequent updates and improvements

Cons of Emscripten

• More complex setup and usage compared to the WebAssembly spec
• May introduce overhead due to its comprehensive nature
• Potential compatibility issues with some C/C++ codebases

Code Comparison

Emscripten (compiling C to WebAssembly):

#include <emscripten.h>
#include <stdio.h>

int main() {
    printf("Hello, WebAssembly!\n");
    return 0;
}

WebAssembly spec (WAT format):

(module
  (import "console" "log" (func $log (param i32 i32)))
  (memory 1)
  (data (i32.const 0) "Hello, WebAssembly!")
  (func (export "main")
    i32.const 0
    i32.const 19
    call $log
  )
)

The Emscripten example shows a C program compiled to WebAssembly, while the WebAssembly spec example demonstrates the same functionality using the WebAssembly Text Format (WAT). Emscripten provides a more familiar environment for C/C++ developers, while the WebAssembly spec offers a lower-level representation of WebAssembly modules.

Pros of Wasmer

• Provides a complete WebAssembly runtime implementation
• Offers cross-platform support and easy integration with various programming languages
• Includes additional features like WASI support and a package manager (WAPM)

Cons of Wasmer

• More complex and larger codebase compared to the spec
• May deviate from the official WebAssembly specification in some implementations
• Requires more frequent updates to keep up with WebAssembly ecosystem changes

Code Comparison

WebAssembly spec (example of a simple module):

(module
  (func $add (param $a i32) (param $b i32) (result i32)
    local.get $a
    local.get $b
    i32.add)
  (export "add" (func $add)))

Wasmer (example of using the runtime in Rust):

use wasmer::{Store, Module, Instance};

let module = Module::from_file(&store, "add.wasm")?;
let instance = Instance::new(&module, &imports)?;
let add = instance.exports.get_function("add")?;
let result = add.call(&[42.into(), 1.into()])?;

Pros of assemblyscript

• Easier learning curve for developers familiar with TypeScript
• Provides a higher-level abstraction for WebAssembly development
• Includes a standard library with common data structures and utilities

Cons of assemblyscript

• Limited to a subset of TypeScript features
• May introduce overhead compared to direct WebAssembly implementation
• Less flexibility in low-level optimizations

Code Comparison

assemblyscript:

export function add(a: i32, b: i32): i32 {
  return a + b;
}

spec (WebAssembly text format):

(module
  (func $add (param $a i32) (param $b i32) (result i32)
    local.get $a
    local.get $b
    i32.add))

Summary

The spec repository contains the official WebAssembly specification, while assemblyscript is a high-level language that compiles to WebAssembly. assemblyscript offers a more familiar syntax for TypeScript developers and includes helpful abstractions, but may sacrifice some low-level control and performance optimizations. The spec provides a lower-level representation of WebAssembly, allowing for more precise control but requiring more expertise to work with directly.

Pros of binaryen

• Provides a comprehensive toolkit for WebAssembly compilation and optimization
• Offers a C++ API for manipulating WebAssembly modules programmatically
• Includes various tools like wasm2js and wasm-opt for WebAssembly processing

Cons of binaryen

• Focuses on tooling rather than the core WebAssembly specification
• May have a steeper learning curve for developers new to WebAssembly
• Requires additional setup and integration compared to using the spec directly

Code Comparison

spec:

(module
  (func $add (param $a i32) (param $b i32) (result i32)
    local.get $a
    local.get $b
    i32.add))

binaryen (C++ API):

Module module;
Function* add = module.addFunction("add", 
  FunctionType::get(i32, {i32, i32}),
  {i32},
  Builder(module).makeBlock({
    Builder(module).makeLocalGet(0, i32),
    Builder(module).makeLocalGet(1, i32),
    Builder(module).makeBinary(AddInt32)
  })
);

The spec repository focuses on defining the WebAssembly standard, while binaryen provides tools and APIs for working with WebAssembly modules. The spec example shows raw WebAssembly text format, whereas the binaryen example demonstrates how to programmatically create a similar function using its C++ API.

Pros of wasm-tools

• Provides a comprehensive suite of tools for working with WebAssembly
• Offers more practical utilities for developers, including parsing, validation, and transformation of WASM modules
• Actively maintained with frequent updates and contributions from the community

Cons of wasm-tools

• Focuses on tooling rather than the core specification, which may not be suitable for those seeking in-depth understanding of WebAssembly internals
• May have a steeper learning curve for beginners due to its more extensive feature set

Code Comparison

spec:

(module
  (func $add (param $a i32) (param $b i32) (result i32)
    local.get $a
    local.get $b
    i32.add))

wasm-tools:

use wasm_tools::parser::parse;

let wasm = parse(r#"(module (func (export "add") (param i32 i32) (result i32) local.get 0 local.get 1 i32.add))"#)?;

Summary

While spec focuses on defining the WebAssembly standard, wasm-tools provides practical tools for working with WebAssembly. spec is essential for understanding the core concepts and specifications, while wasm-tools offers more hands-on utilities for developers working with WASM modules. The choice between the two depends on whether you need to study the specification or work with WebAssembly in practice.