Enum Message 

pub enum Message {
    Human(HumanMessage),
    Ai(AiMessage),
    System(SystemMessage),
    Tool(ToolMessage),
}

A single message in an LLM conversation.

Variants

Human(HumanMessage)

User input.

Ai(AiMessage)

Assistant response.

System(SystemMessage)

System prompt or instruction.

Tool(ToolMessage)

Tool execution result.

Implementations

impl Message

Convenience constructors.

pub fn human(content: impl Into<String>) -> Self

Build a Human message with text only.

pub fn human_with_parts( content: impl Into<String>, parts: Vec<ContentPart>, ) -> Self

Build a Human message that carries multimodal parts alongside text. Providers that support multimodal will serialize the parts; others silently ignore them and use the text content alone.

pub fn ai(content: impl Into<String>) -> Self

Build an Ai message with text only (no tool calls, no parts).

pub fn ai_with_parts( content: impl Into<String>, parts: Vec<ContentPart>, ) -> Self

Build an Ai message with multimodal parts alongside text.

pub fn system(content: impl Into<String>) -> Self

Build a System message.

pub fn tool(call_id: impl Into<String>, content: impl Into<String>) -> Self

Build a Tool message.

pub fn content(&self) -> &str

Get the message’s primary text content (empty string for messages that are tool-call-only with no text).

pub fn tool_calls(&self) -> &[ToolCall]

Returns the tool calls if this is an Ai message; empty otherwise.

pub fn has_tool_calls(&self) -> bool

True if this is an Ai message with at least one tool call.

pub fn parts(&self) -> &[ContentPart]

Multimodal parts on a Human or Ai message. Empty for System / Tool (they don’t carry multimodal content).

Trait Implementations

impl Clone for Message

fn clone(&self) -> Message

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Message

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Message

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl From<&str> for Message

fn from(s: &str) -> Self

Converts to this type from the input type.

impl From<String> for Message

fn from(s: String) -> Self

Converts to this type from the input type.

impl PartialEq for Message

fn eq(&self, other: &Message) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for Message

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Message