Struct RunnableSeq 

pub struct RunnableSeq { /* private fields */ }

Chains multiple Runnables sequentially — output of step N becomes input of step N+1.

This is the Rust equivalent of Python’s RunnableSeq / RunnableSequence. Requires at least 2 steps (first = node logic, rest = writers/post-processors).

In LangGraph’s Pregel engine, every node is assembled as: RunnableSeq(node_func, channel_write)

Implementations

impl RunnableSeq

pub fn new(name: impl Into<String>, steps: Vec<Arc<dyn Runnable>>) -> Self

Create a new sequence. Panics if fewer than 2 steps.

pub fn new_relaxed( name: impl Into<String>, steps: Vec<Arc<dyn Runnable>>, ) -> Self

Create with any number of steps (1 is allowed for degenerate cases).

pub fn len(&self) -> usize

Number of steps in the sequence.

pub fn is_empty(&self) -> bool

Whether the sequence is empty.

Trait Implementations

impl Runnable for RunnableSeq

fn invoke( &self, input: &JsonValue, config: &RunnableConfig, ) -> Result<JsonValue, RunnableError>

Execute synchronously.

fn ainvoke<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, input: &'life1 JsonValue, config: &'life2 RunnableConfig, ) -> Pin<Box<dyn Future<Output = Result<JsonValue, RunnableError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Execute asynchronously.

fn name(&self) -> &str

Human-readable name for tracing/debugging.