langchain.js
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    Function task

    • Define a LangGraph task using the task function.

      Tasks can only be called from within an entrypoint or from within a StateGraph. A task can be called like a regular function with the following differences:

      • When a checkpointer is enabled, the function inputs and outputs must be serializable.
      • The wrapped function can only be called from within an entrypoint or StateGraph.
      • Calling the function produces a promise. This makes it easy to parallelize tasks.

      Type Parameters

      • ArgsT extends unknown[]

        The type of arguments the task function accepts

      • OutputT

        The type of value the task function returns

      Parameters

      Returns (...args: ArgsT) => Promise<OutputT>

      A proxy function that accepts the same arguments as the original and always returns the result as a Promise

      const addOne = task("add", async (a: number) => a + 1);

      const workflow = entrypoint("example", async (numbers: number[]) => {
        const promises = numbers.map(n => addOne(n));
        const results = await Promise.all(promises);
        return results;
      });

      // Call the entrypoint
      await workflow.invoke([1, 2, 3]); // Returns [2, 3, 4]

      const addOne = task({
          name: "add",
          retry: { maxAttempts: 3 }
        },
        async (a: number) => a + 1
      );

      const workflow = entrypoint("example", async (numbers: number[]) => {
        const promises = numbers.map(n => addOne(n));
        const results = await Promise.all(promises);
        return results;
      });

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