### Basic .calc script interpreter in Rust

Source: https://github.com/typst/comemo/blob/main/README.md

Demonstrates a simple Rust interpreter for a custom `.calc` scripting language. It evaluates expressions and handles nested `eval` statements by recursively reading files. This version lacks incremental capabilities and would recompute everything on any file change.

```rust
/// Evaluate a `.calc` script.
fn evaluate(script: &str, files: &Files) -> i32 {
    script
        .split('+')
        .map(str::trim)
        .map(|part| match part.strip_prefix("eval ") {
            Some(path) => evaluate(&files.read(path), files),
            None => part.parse::<i32>().unwrap(),
        })
        .sum()
}

impl Files {
    /// Read a file from storage.
    fn read(&self, path: &str) -> String {
        ...
    }
}
```

--------------------------------

### Integrate comemo for incremental computation in Rust

Source: https://github.com/typst/comemo/blob/main/README.md

Shows how to modify the `.calc` script interpreter to use `comemo` for constrained memoization. It applies `#[memoize]` to the evaluation function and `#[track]` to the file access implementation, enabling fine-grained dependency tracking for incremental updates.

```rust
use comemo::{memoize, track, Tracked};

/// Evaluate a `.calc` script.
#[memoize]
fn evaluate(script: &str, files: Tracked<Files>) -> i32 {
    ...
}

#[track]
impl Files {
    /// Read a file from storage.
    fn read(&self, path: &str) -> String {
        ...
    }
}
```

--------------------------------

### Add comemo dependency to Cargo.toml

Source: https://github.com/typst/comemo/blob/main/README.md

Specifies the comemo library as a dependency in a Rust project's `Cargo.toml` file, enabling its use for incremental computation.

```toml
[dependencies]
comemo = "0.4"
```

=== COMPLETE CONTENT === This response contains all available snippets from this library. No additional content exists. Do not make further requests.