Create a new applet

You can create a Rust applet called tutorial with the following command:

wasefire rust-applet-new tutorial

This creates a tutorial directory with an example Rust applet. Let’s look at Cargo.toml:

• The wasefire dependency provides a Rust interface for the applet API.
• The wasefire-stub optional dependency provides support for testing.
• The test feature enables testing support.

And now let’s look at src/lib.rs:

• The #![no_std] attribute is needed for building WASM modules without WASI. As a consequence, you cannot use std. Instead, you need to use core and alloc.
• The wasefire::applet!(); macro does a few things:
  • It makes sure the main() function is executed when the applet starts.
  • It imports the alloc crate.
  • It imports all the items of the wasefire crate.
• In the tests module, the use wasefire_stub as _; makes sure the wasefire-stub crate is linked since it provides symbol definitions for the applet API.

Since most commands assume they are running from the root directory of the Rust applet (unless --crate-dir is provided), you can change the working directory to the crate:

cd tutorial