Enable tool support for ollama

[alappe]

Adds basic support for tools with ollama v0.3, tested with the hairbrush example:

alias LangChain.Function
alias LangChain.Message
alias LangChain.Chains.LLMChain
alias LangChain.ChatModels.ChatOllamaAI


# map of data we want to be passed as `context` to the function when
# executed.
custom_context = %{
  "user_id" => 123,
  "hairbrush" => "drawer",
  "dog" => "backyard",
  "sandwich" => "kitchen"
}

# a custom Elixir function made available to the LLM
custom_fn =
  Function.new!(%{
    name: "custom",
    description: "Returns the location of the requested element or item.",
    parameters_schema: %{
      type: "object",
      properties: %{
        thing: %{
          type: "string",
          description: "The thing whose location is being requested."
        }
      },
      required: ["thing"]
    },
    function: fn %{"thing" => thing} = _arguments, context ->
      # our context is a pretend item/location location map
      {:ok, context[thing]}
  end
  })

# create and run the chain
{:ok, updated_chain, %Message{} = message} =
  LLMChain.new!(%{
    llm: ChatOllamaAI.new!(%{model: "llama3.1", verbose: true}),
    custom_context: custom_context,
    verbose: true
  })
  |> LLMChain.add_tools(custom_fn)
  |> LLMChain.add_message(Message.new_user!("Where is the hairbrush located?"))
  |> LLMChain.run(mode: :while_needs_response)

# print the LLM's answer
IO.puts(message.content)
#=> "The hairbrush is located in the drawer."

[brainlid]

Just reviewing the code, it looks good!

Can you add some tests? I'd like to see tests for the following:

• for_api
• get_parameters
• call using Mimic to avoid doing a live call
• do_process_response

Having tests really helps the maintainability of the project since I'm not easily able to test all the different chat models.

Feel free to ask questions if you need help with any of that. Thanks!

[alappe]

I added several tests to the best of my knowledge (I'm new to langchain). Please have a look…

[brainlid]

Thank you for adding tests! Sorry I was slow to respond.

I added some specific requests. The one example I gave about assert [%{"function" => _} | _] = data.tools applies to all the other tests as well.

[brainlid]

Let's flatten this out into explicit aliases.

  alias LangChain.ChatModels.ChatOllamaAI
  alias LangChain.Function
  alias LangChain.FunctionParam

[brainlid]

One of the main goals with the test is to verify it's formatting the data as the targeted LLM expects it. Not just that it's a map with a "function" key. Also, because of the test setup, you can safely make assumptions about the expected data. For example...

assert [%{} = result_data] = data.tools

# now create a result_data assertion

We want to test that the LangChain.Function data structure is structured how the supported Ollama server expects it to be. What does it expect things to be called? Anything different or unusual?