@restlessronin the main reason was that I needed something quick, and I assumed that major libraries (such as LangChain which I use in production) will take a while to implement it. I did check openai_ex’s GitHub homepage but since it didn’t mention responses, I thought they are not implemented yet (and I failed to check the git log).

But also, I wanted something lightweight, in “SDKs with Req” fashion. For example, I use @brainlid’s LangChain in production, because it supports many providers, such as OpenAI/Anthropic/Google/Groq/xAI/many others with just a parameter change, and it is mature and well tested, but the simplest usage example is something like this:

{:ok, updated_chain} =
  %{llm: ChatOpenAI.new!(%{model: "gpt-4o"})}
  |> LLMChain.new!()
  |> LLMChain.add_message(Message.new_user!("Testing, testing!"))
  |> LLMChain.run()

Compare this to just

{:ok, response} = Responses.create("gpt-4o", "Testing, testing!")

Or another example (and this is not a ding to LangChain), to get the number of tokens you need to define a callback function. I understand how it might be useful in some contexts, but it can also be a bit cumbersome in others.

I found that I almost always create simple wrappers, and wanted to design a new library from scratch - without any legacy luggage, like the need to support chat completions or other providers - to be simple and delightful in use.

And of course, last but not the least, it was an excuse to try Claude Code. I am very satisfied with the result of this experiment: it can create something quite useful with minimal guidance.

Ah no. It works correctly. Enum works on enumerables, not lists. In any case, the user guide / tutorial is basically my test suite. It gets run after every change to the API, so something like this would get caught pretty early. Doing it this way also ensures that the documentation is always up to date with the library.

Here’s my subjective experience comparing Claude Code to Cursor, which I use daily as my main tool. (I say “subjective” because, even when the underlying models—like Claude Sonnet 3.7—are the same, these tools differ in their behaviors in ways that are hard to measure.)

Claude Code feels a bit smarter and gets to the “right answer” more quickly, with fewer revisions. In my opinion, it’s about 2-3 times faster, based on the time from when I give a prompt to when I get a mostly working solution.

The trade-off is the cost. I suspect that, like the early days of Uber or Lyft, some venture capital money is being spent to keep prices low for AI code editors. For example, I spent around $5 on Claude Code credits (mostly trying to get streaming to work—more on that later). With Cursor’s $20 monthly subscription for 500 fast requests, that’s like using 125 requests. If I’d done the same task in Cursor, I probably wouldn’t have used more than 10-15 requests—a huge difference. (Also, someone on X recommended trae.ai, which is currently free, because Alibaba or some other Chinese internet giant is paying for your tokens.)

I had two main challenges when creating openai_responses:

1. The streaming did not work initially, because it didn’t know about Req’s :into parameter and hallucinated that it needs hackney to make it work. The solution, after many trials (including asking Grok 3 to help), was to just drop instructor_ex’s source file which implements streaming and telling Claude, “do it this way”.

2. The Kino.Frame streaming example in Livebook was originally enclosed with another spawn, and didn’t work (some weird interactions between Elixir processes I guess). Neither Claude nor Grok knew how to fix it until I just decided to try to remove the enclosing spawn, which was really not needed.

Also, the examples it wrote for me to include in Livebook tutorial were overly complex - that’s the only part of the library that I decided to write myself.