Embedding WebAssembly in your Rust application Wasmer

Wasmer is a WebAssembly runtime designed to run both standalone and embedded.

The crate wasmer-runtime exposes an easy to use and safe api for compiling, creating imports, and calling WebAssembly from your own library.

This tutorial goes over how to make a simple wasm application and run it using the wasmer-runtime!

Creating a Wasm Application

Our sample application is just a basic “Hello, World!” program. Because WebAssembly doesn’t inherently have any way to print to the command line, we have to import such a function from our environment.

In this case, we define an imported print_str function.

When the hello_wasm function is called by the embedder, it will proceed to call the imported print_str function with a pointer to the “Hello, World!” string and its length as arguments.

Embedding WebAssembly using Wasmer!

This example shows to use use the wasmer-runtime crate to compile and run WebAssembly!

Since our Wasm application imported a function print_str , we must create an ImportObject containing the implementation of that function.

While you can manually (and unsafely) fill in the import object yourself, we’ve defined a useful macro that does function signature checking automatically to make it easier and safer.

This example is hosted on Github . Check out the Readme for instructions on how to try it out for yourself!

If you have feedback, issues, or feature requests please open an issue in our Github repository .

We look forward to what cool things you build with WebAssembly and our new embeddable runtime!