Expressions and bindings

What

Expressions and bindings are the foundation of Musi reading. Start with a bound name, then read later expressions from the top of the file down.

let port := 8080;
port;

Why

This model is predictable for Python/JS users: each line can introduce data, then later lines consume it.

How

Use let for names and ; for expression boundaries.

(
  let base := 8000;
  base + 80
);

Case expressions are the branching form in this surface.

let Port := data {
  | Configured : Int
  | Default
};

let port : Port := .Configured(8080);
case port of (
| .Configured(port) => port
| .Default => 3000
);

When

Use these patterns when you want readable scripts, data preparation, and deterministic command flow.

Analogy

Like a recipe card: bind each ingredient first, then assemble a final step.

Try it

Read the two snippets, then move to Functions and calls.