AssemblyScript.md

WebAssembly with AssemblyScript

Before we begin, it’s necessary that you have npm in your system.

1. Setting up the environment

   To install AssemblyScript on your local system, run the command given below, and to install Wasmtime to run our .wasm file, you can take a look at their website.

   npm install -g assemblyscript
   

   We also need to install as-wasi. It is an easy to use API for the AssemblyScript WASI bindings. By bindings, we mean the declared functions that would map to the WASI host functions. The command to do the same is :

   npm install --save as-wasi
   

2. Code

   Open your preferred text editor and make a file with .ts extension.

   The fibonacci code in AssemblyScript is as follows :

   import "wasi";
   import { Console } from "as-wasi";
   
   export function fibo (n: i32): i32 {
       if(n==1 || n==0){
         return n;
       }
       else{
         return fibo(n-1) + fibo(n-2);
       }
   }
   
   let a: i32 = fibo(7);
   Console.log(a.toString());
   

   We need to import wasi to add some nice defaults for compiling to WASI and we need to import Console to write to stdout.

3. Compiling the code

   To compile your AssemblyScript code, simply run :

   asc fibo.ts -o fibo.wasm
   

   This would generate a fibo.wasm file in your working directory.

4. Running .wasm file in Wasmtime

   To run our .wasm file in wasmtime, run the following command

   wasmtime fibo.wasm