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WebAssembly with Swift

note
  • WebAssembly support for Swift is good thanks to SwiftWasm.
  • SwiftWasm compiles Swift code to WebAssembly.

Install Swift​

To install Docker on your local system, refer the official guide.

First, we need to pull the docker image and run it in an interactive mode; we would be accessing the container from its bash. To do the same, run the following command.

docker run -v `pwd`:/swift --rm -it ghcr.io/swiftwasm/swift:latest /bin/bash

Swift code​

The fibonacci code in Swift is as follows :

func fib(n: UInt) -> UInt {
    if n <= 1 {
        return n
    }

    return fib(n: n-1) + fib(n: n-2)
}

print("Swift - Fibonacci sequence example\n")

let arguments = CommandLine.arguments

var n:UInt
if (arguments.count > 1) {
    for i in 1...arguments.count-1 {
        if let n = UInt(arguments[i]) {
            print("Fibonacci sequence number at index \(n) is \(fib(n: n))\n")
        } else {
            print("Failed to parse argument into a number: \(arguments[i])\n")
        }
    }
} else {
    print("Enter a non-negative number:\n")
    if let line = readLine() {
        if let n = UInt(line) {
            print("Fibonacci sequence number at index \(n) is \(fib(n: n))\n")
        } else {
            print("Could not convert \(line) to integer.\n")    
        }
    } else {
        print("Could not read user input.\n")   
    }
}
tip

Access the Swift codex repository for code samples, including the fibonacci example.

Compile Swift to Wasm​

To compile your Swift code to Wasm, simply run:

swiftc -target wasm32-unknown-wasi /swift/fibonacci.swift -o /swift/fibonacci.wasm

Run with Enarx​

enarx run fibonacci.wasm