View Source LangChain.MessageDelta (LangChain v0.3.0-rc.0)

Models a "delta" message from a chat LLM. A delta is a small chunk, or piece of a much larger complete message. A series of deltas are used to construct the complete message.

Delta messages must be applied in order for them to be valid. Delta messages can be combined and transformed into a LangChain.Message once the final piece is received.

Roles

:unknown - The role data is missing for the delta.
:assistant - Responses coming back from the LLM.

Tool Usage

Tools can be used or called by the assistant (LLM). A tool call is also split across many message deltas and must be fully assembled before it can be executed.

Summary

Types

t()

Functions

merge_delta(primary, delta_part)

Merge two MessageDelta structs. The first MessageDelta is the primary one that smaller deltas are merged into.

new(attrs \\ %{})

Create a new MessageDelta that represents a message chunk.

new!(attrs \\ %{})

Create a new MessageDelta that represents a message chunk and return it or raise an error if invalid.

to_message(delta)

Convert the MessageDelta to a Message. Can only convert a fully complete MessageDelta.

Types

t()

@type t() :: %LangChain.MessageDelta{
  content: term(),
  index: term(),
  role: term(),
  status: term(),
  tool_calls: term()
}

Functions

merge_delta(primary, delta_part)

@spec merge_delta(nil | t(), t()) :: t()

Merge two MessageDelta structs. The first MessageDelta is the primary one that smaller deltas are merged into.

iex> delta_1 =
...>   %LangChain.MessageDelta{
...>     content: nil,
...>     index: 0,
...>     tool_calls: [],
...>     role: :assistant,
...>     status: :incomplete
...>   }
iex> delta_2 =
...>   %LangChain.MessageDelta{
...>     content: "Hello",
...>     index: 0,
...>     tool_calls: [],
...>     role: :unknown,
...>     status: :incomplete
...>   }
iex> LangChain.MessageDelta.merge_delta(delta_1, delta_2)
%LangChain.MessageDelta{content: "Hello", status: :incomplete, index: 0, role: :assistant, tool_calls: []}

A set of deltas can be easily merged like this:

[first | rest] = list_of_delta_message

Enum.reduce(rest, first, fn new_delta, acc ->
  MessageDelta.merge_delta(acc, new_delta)
end)

new(attrs \\ %{})

@spec new(attrs :: map()) :: {:ok, t()} | {:error, Ecto.Changeset.t()}

Create a new MessageDelta that represents a message chunk.

new!(attrs \\ %{})

@spec new!(attrs :: map()) :: t() | no_return()

Create a new MessageDelta that represents a message chunk and return it or raise an error if invalid.

to_message(delta)

@spec to_message(t()) :: {:ok, LangChain.Message.t()} | {:error, String.t()}

Convert the MessageDelta to a Message. Can only convert a fully complete MessageDelta.

This is assumed to be the result of merging all the received MessageDeltas. An error is returned if the status is :incomplete.

If the MessageDelta fails to convert to a LangChain.Message, an error is returned with the reason.