Trait BaseChatModel 

pub trait BaseChatModel: BaseLanguageModel<Vec<Message>, LLMResult> {
    // Required methods
    fn chat<'life0, 'async_trait>(
        &'life0 self,
        messages: Vec<Message>,
        config: Option<RunnableConfig>,
    ) -> Pin<Box<dyn Future<Output = Result<LLMResult, Self::Error>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait;
    fn stream_chat<'life0, 'async_trait>(
        &'life0 self,
        messages: Vec<Message>,
        config: Option<RunnableConfig>,
    ) -> Pin<Box<dyn Future<Output = Result<Pin<Box<dyn Stream<Item = Result<StreamChunk, Self::Error>> + Send>>, Self::Error>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait;

    // Provided methods
    fn chat_with_system<'life0, 'async_trait>(
        &'life0 self,
        system: String,
        messages: Vec<Message>,
    ) -> Pin<Box<dyn Future<Output = Result<LLMResult, Self::Error>> + Send + 'async_trait>>
       where Self: Sync + 'async_trait,
             'life0: 'async_trait { ... }
    fn bind_tools(
        &self,
        _tools: Vec<ToolDefinition>,
    ) -> Option<Box<dyn BaseChatModel<Error = Self::Error> + Send + Sync>> { ... }
}

Base trait for chat models.

Extends BaseLanguageModel for chat scenarios. Accepts message list as input, returns AI message.

Required Methods

fn chat<'life0, 'async_trait>( &'life0 self, messages: Vec<Message>, config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<LLMResult, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Chat with the model.

Arguments

• messages - Message list.
• config - Optional configuration.

Returns

LLM result.

fn stream_chat<'life0, 'async_trait>( &'life0 self, messages: Vec<Message>, config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<Pin<Box<dyn Stream<Item = Result<StreamChunk, Self::Error>> + Send>>, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Stream chat with the model.

Arguments

• messages - Message list.
• config - Optional configuration.

Returns

Stream of StreamChunk items. Chunks carry the text delta; the final chunk may additionally carry StreamChunk::token_usage when the provider reports usage.

Provided Methods

fn chat_with_system<'life0, 'async_trait>( &'life0 self, system: String, messages: Vec<Message>, ) -> Pin<Box<dyn Future<Output = Result<LLMResult, Self::Error>> + Send + 'async_trait>>

where Self: Sync + 'async_trait, 'life0: 'async_trait,

Chat with system prompt.

Arguments

• system - System prompt.
• messages - Message list.

Returns

LLM result.

fn bind_tools( &self, _tools: Vec<ToolDefinition>, ) -> Option<Box<dyn BaseChatModel<Error = Self::Error> + Send + Sync>>

Bind tool definitions for function calling.

Returns Some(model) with the tools attached when the provider supports tool calling; returns None when it does not. The default returns None, signalling a hard capability limit — callers MUST treat None as “this model cannot call tools” and branch accordingly (e.g. fall back to text-only prompting). Providers that support function calling (OpenAI, Ollama) override this.

This is an explicit result, not a silent degrade: None is the honest answer that tool-calling is unavailable on this model.

Trait Implementations

impl<E> BaseChatModel for Box<dyn BaseChatModel<Error = E> + Send + Sync>

where E: Error + Send + Sync + 'static,

fn chat<'life0, 'async_trait>( &'life0 self, messages: Vec<Message>, config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<LLMResult, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Chat with the model.

fn stream_chat<'life0, 'async_trait>( &'life0 self, messages: Vec<Message>, config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<Pin<Box<dyn Stream<Item = Result<StreamChunk, Self::Error>> + Send>>, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Stream chat with the model.

fn bind_tools( &self, tools: Vec<ToolDefinition>, ) -> Option<Box<dyn BaseChatModel<Error = Self::Error> + Send + Sync>>

Bind tool definitions for function calling.

fn chat_with_system<'life0, 'async_trait>( &'life0 self, system: String, messages: Vec<Message>, ) -> Pin<Box<dyn Future<Output = Result<LLMResult, Self::Error>> + Send + 'async_trait>>

where Self: Sync + 'async_trait, 'life0: 'async_trait,

Chat with system prompt.

impl<E> BaseLanguageModel<Vec<Message>, LLMResult> for Box<dyn BaseChatModel<Error = E> + Send + Sync>

where E: Error + Send + Sync + 'static,

fn model_name(&self) -> &str

Returns the model name.

fn get_num_tokens(&self, text: &str) -> usize

Calculates token count for text.

fn temperature(&self) -> Option<f32>

Returns the temperature parameter.

fn max_tokens(&self) -> Option<usize>

Returns the max tokens limit.

fn with_temperature(self, _temp: f32) -> Self

where Self: Sized,

Sets the temperature parameter.

fn with_max_tokens(self, _max: usize) -> Self

where Self: Sized,

Sets the max tokens limit.

impl<E> Runnable<Vec<Message>, LLMResult> for Box<dyn BaseChatModel<Error = E> + Send + Sync>

where E: Error + Send + Sync + 'static,

type Error = E

Error type.

fn invoke<'life0, 'async_trait>( &'life0 self, input: Vec<Message>, config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<LLMResult, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Transforms single input to output.

fn stream<'life0, 'async_trait>( &'life0 self, input: Vec<Message>, config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<Pin<Box<dyn Stream<Item = Result<LLMResult, Self::Error>> + Send>>, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Streaming output - for real-time responses (LLM, etc).

fn batch<'life0, 'async_trait>( &'life0 self, inputs: Vec<Input>, config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<Vec<Output>, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Batch processing - transforms multiple inputs to outputs.

fn batch_as_completed<'life0, 'async_trait>( &'life0 self, inputs: Vec<Input>, config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<Vec<(usize, Output)>, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Batch processing that returns results in completion order.

fn transform<'life0, 'async_trait>( &'life0 self, input: Pin<Box<dyn Stream<Item = Result<Input, Self::Error>> + Send>>, config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<Pin<Box<dyn Stream<Item = Result<Output, Self::Error>> + Send + '_>>, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Stream-to-stream transformation - the core of LCEL streaming.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementations on Foreign Types

impl<E> BaseChatModel for Box<dyn BaseChatModel<Error = E> + Send + Sync>

where E: Error + Send + Sync + 'static,

fn chat<'life0, 'async_trait>( &'life0 self, messages: Vec<Message>, config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<LLMResult, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

fn stream_chat<'life0, 'async_trait>( &'life0 self, messages: Vec<Message>, config: Option<RunnableConfig>, ) -> Pin<Box<dyn Future<Output = Result<Pin<Box<dyn Stream<Item = Result<StreamChunk, Self::Error>> + Send>>, Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

fn bind_tools( &self, tools: Vec<ToolDefinition>, ) -> Option<Box<dyn BaseChatModel<Error = Self::Error> + Send + Sync>>

Implementors

impl BaseChatModel for RouterLLM

impl<L> BaseChatModel for TokenTrackingLLM<L>

where L: BaseChatModel + Send + Sync,