Error Handling

The Helios Engine uses a custom error type called HeliosError to represent all possible errors that can occur within the framework. This chapter will cover the different types of errors and how to handle them.

HeliosError

The HeliosError enum is the single error type used throughout the Helios Engine. It has the following variants:

  • ConfigError(String): An error related to configuration.
  • LLMError(String): An error related to the Language Model (LLM).
  • ToolError(String): An error related to a tool.
  • AgentError(String): An error related to an agent.
  • NetworkError(#[from] reqwest::Error): An error related to a network request.
  • SerializationError(#[from] serde_json::Error): An error related to serialization or deserialization.
  • IoError(#[from] std::io::Error): An I/O error.
  • TomlError(#[from] toml::de::Error): An error related to parsing TOML.
  • LlamaCppError(String): An error from the Llama C++ backend (only available with the local feature).

Result<T>

The Helios Engine also provides a convenient Result type alias that uses the HeliosError as the error type:

#![allow(unused)]
fn main() {
pub type Result<T> = std::result::Result<T, HeliosError>;
}

This means that you can use the ? operator to propagate errors in your code, just like you would with a standard std::result::Result.

Handling Errors

Here's an example of how to handle errors in the Helios Engine:

use helios_engine::{Agent, Config, CalculatorTool, Result};

#[tokio::main]
async fn main() {
    if let Err(e) = run().await {
        eprintln!("Error: {}", e);
    }
}

async fn run() -> Result<()> {
    let config = Config::from_file("config.toml")?;

    let mut agent = Agent::builder("MathAgent")
        .config(config)
        .system_prompt("You are a helpful math assistant.")
        .tool(Box::new(CalculatorTool))
        .max_iterations(5)
        .build()
        .await?;

    let response = agent.chat("What is 15 * 8 + 42?").await?;
    println!("Agent: {}", response);

    Ok(())
}

In this example, the run function returns a Result<()>. If any of the operations within the function fail, the error will be propagated up to the main function, where it will be printed to the console.