cohere-ai/melody

cohere-ai/melody

Description: Templating rendering and generation parsing for Cohere models.

Language: Rust

License: MIT

Stars: 2

Forks: 1

Open issues: 0

Created: 2025-10-10T17:32:30Z

Pushed: 2026-06-09T21:20:52Z

Default branch: main

Fork: no

Archived: no

README:

melody

Templating rendering and generation parsing for Cohere models.

Dev Setup

1. Install Rust from rustup.rs. 2. Install rust-analyzer for IDE support. 3. make rust-test && make rust-lint to ensure everything is working.

Examples

The examples/ directory contains several example programs demonstrating how to use the Melody parsing library in Rust. You can run them using:

cargo run --example basic

Usage

Parsing

use cohere_melody::parsing::Filter;
use cohere_melody::*;

// Create a filter with options
let options = parsing::FilterOptions::new().cmd3();

let mut filter = parsing::new_filter(options);

// Simulate text
let citation_text = "Hello world!";

// Write text — returns an aggregated result
let result = filter.write_decoded(citation_text);

if let Some(text) = &result.content {
println!(" Content: {text}");
}
for citation in &result.citations {
println!(
" Citation: {} (indices {}-{})",
citation.text, citation.start_index, citation.end_index
);
}

// Flush remaining tokens
let final_result = filter.flush_partials();

Templating

use cohere_melody::parsing::Filter;
use cohere_melody::*;

// Assemble inputs into the template (e.g. conversation history)
let options = templating::RenderCmd4Options {
messages: vec![
templating::types::Message {
role: templating::types::Role::System,
content: vec![templating::types::Content {
content_type: templating::types::ContentType::Text,
text: Some("You are a helpful assistant.".to_string()),
thinking: None,
image: None,
document: None,
}],
tool_calls: vec![],
tool_call_id: None,
citations: vec![],
},
templating::types::Message {
role: templating::types::Role::User,
content: vec![templating::types::Content {
content_type: templating::types::ContentType::Text,
text: Some("Hello Command!.".to_string()),
thinking: None,
image: None,
document: None,
}],
tool_calls: vec![],
tool_call_id: None,
citations: vec![],
},
],
..Default::default()
};

// Render prompt
let prompt = templating::render_cmd4(&options).unwrap();

Releasing

Bump the version in Cargo.toml and push to main. The CI will automatically create a GitHub release, build wheels for all platforms, and publish to PyPI.

Building Python Bindings

Prerequisites (from pyo3)

1. Recommended install uv 2. From root directory, run:

make python-bindings

3. Test the bindings:

cd rust
uv run python -c "import cohere_melody;"

Debugging

You may run into issues calling the Rust static library from other languages (e.g. Golang via CGO). One effective way to debug these issues is to:

1. Build the library in debug mode. You can do this by adding these lines to the Cargo.toml file:

[profile.release]
debug = true

and then building the library normally: make rust-build-with-tokenizers.

2. Create a binary to debug. In Golang, I create a binary from a test:

go test -count=1 ./gobindings/... -c

3. Use gdb (brew install gdb on macOS).

gdb ./gobindings.test
break melody_render_cmd3
run

4. When it hits the breakpoint, you can step through the Rust code to see where things might be going wrong.