← Back to 20250617

08 PATH

Documentation for 08_PATH from the Ds ex repository.

The Pragmatic Path: From Grand Vision to Achievable Steps

The new philosophy is: Build it inside DSPEx first. Once it’s mature and proves its value, then consider extracting it into a separate library.

This is a common and highly effective way to evolve a software ecosystem. Build the monolith first, then break it apart when the boundaries become clear and the need arises.

Here is your new, achievable, step-by-step plan:

Step 0: Stabilize the Now (1-2 Days)

  • Goal: Stop the bleeding. Make what you have less fragile.
  • Action:
    1. Simplify Foundation Interaction: Instead of the huge try/rescue blocks, create a tiny internal DSPEx.Foundation.Client module. This module will be the only place in your app that calls Foundation. It will contain the try/rescue block. If Foundation fails, this client will return a standard {:error, :foundation_unavailable} tuple.
    2. Now, all your other DSPEx modules can call DSPEx.Foundation.Client.emit_telemetry(...) and just handle a simple error tuple. This contains the problem and makes your core logic cleaner.

Step 1: Build the Exdantic MVP… as a single module. (1 Week)

  • Goal: Get the core value of Ecto-based structured data without building a whole new library.
  • Action:
    1. Create a new file: dspex/schema.ex.
    2. Inside, create defmodule DSPEx.Schema.
    3. Implement the use DSPEx.Schema macro as we discussed. It will use Ecto.Schema, add the from_llm_map/1 validation function, and the to_json_schema/1 generator.
    4. Crucially, this lives inside DSPEx. It’s just another feature of your library.

Step 2: Build the ExLLMAdapter MVP… as a single function. (1 Week)

  • Goal: Make one real, modern, structured API call work.
  • Action:
    1. Go into dspex/client.ex.
    2. Add a new public function: def request_structured(prompt, schema_module, opts).
    3. Implement the logic we sketched out:
      • It takes a DSPEx.Schema module.
      • It calls DSPEx.Schema.to_json_schema(schema_module).
      • It builds the correct Gemini request body for their “Function Calling” / structured output API.
      • It makes the Req.post call.
      • It gets the JSON back and calls DSPEx.Schema.from_llm_map(json).
  • You are not building a whole library. You are building one function that does the job correctly.

Step 3: Connect the Pieces and Demonstrate Value (A few hours)

  • Goal: Make your PredictStructured module actually use the new stuff and feel like magic.
  • Action:
    1. Refactor DSPEx.PredictStructured.
    2. Its forward function will now call DSPEx.Client.request_structured(...).
    3. Update your QASignature or create a new example schema using use DSPEx.Schema with multiple types (e.g., field :confidence, :float).
    4. Run it. When you see your LLM return a fully-typed, validated Elixir struct from a simple definition, you will have proven the entire concept.

What about Foundation?

Defer the big refactor. For now, Foundation is what it is. You’ve contained the chaos behind the DSPEx.Foundation.Client facade in Step 0. Your new DSPEx.Client.request_structured function can still call DSPEx.Foundation.Client.emit_telemetry to log its calls. It’s not perfect, but it’s contained. You can tackle the bigger platform refactor after.

Your New Reality

This new plan is drastically simpler. You are not building three libraries. You are adding two modules and one function to your existing DSPEx library.

  1. DSPEx.Schema (The Exdantic MVP)
  2. DSPEx.Client.request_structured/3 (The LLM Adapter MVP)
  3. An updated DSPEx.PredictStructured to use them.