package ocaml-ai-sdk

ocaml-ai-sdk

Type-safe, provider-agnostic AI model abstraction for OCaml, inspired by the Vercel AI SDK. Targets wire compatibility with AI SDK v6 so you can pair an OCaml backend with @ai-sdk/react frontends.

Libraries

Quick start

opam install ocaml-ai-sdk

One-shot generation

open Ai_core
open Ai_provider_anthropic

let () =
  Lwt_main.run @@
  let model = Anthropic.create_model "claude-sonnet-4-6" in
  let%lwt result = Generate_text.generate ~model ~prompt:"Say hello" () in
  Lwt_io.printl result.text

Streaming

let () =
  Lwt_main.run @@
  let model = Anthropic.create_model "claude-sonnet-4-6" in
  let%lwt result = Stream_text.stream ~model ~prompt:"Tell me a joke" () in
  Lwt_stream.iter_s Lwt_io.printl result.text_stream

Chat server (with UIMessage protocol)

let handler = Server_handler.create ~model ()
(* Serves SSE responses compatible with useChat() from @ai-sdk/react *)

See examples/ for complete runnable demos including tool use, thinking, structured output, OpenRouter prompt caching, and full-stack Melange apps.

Architecture

ai_provider          Provider abstraction (module types, GADT options)
├── ai_provider_anthropic   Anthropic implementation
├── ai_provider_openai      OpenAI implementation
├── ai_provider_openrouter  OpenRouter implementation
└── ai_core                 Core SDK (generate, stream, UIMessage protocol)

Key design choices:

• Provider options use an extensible GADT (type _ key = ..) for compile-time type-safe provider-specific settings (e.g. thinking budget, cache control, OpenRouter routing)
• Prompt types are role-constrained variants — System accepts only strings, User accepts text + files, etc.
• Streaming uses Lwt_stream.t — stream_text returns synchronously with streams populated by a background Lwt task
• UIMessage protocol emits SSE chunks matching the ai@6 Zod schemas exactly, so useChat() works without adaptation

Anthropic thinking

Anthropic_options.thinking = None omits the thinking request field. Use Some Thinking.Disabled to explicitly disable thinking on models that default to it; Adaptive and Enabled select the corresponding Anthropic modes. effort is independent and is serialized under output_config.

When forwarding Anthropic reasoning blocks, preserve their provider metadata signature. Omitted-display thinking can have empty text, but its signature is required for multi-turn and tool-loop resubmission.

AI SDK v6 compatibility

The UIMessage stream protocol (x-vercel-ai-ui-message-stream: v1) is wire-compatible with:

• @ai-sdk/react 3.x (useChat, useCompletion)
• ai 6.x (core SDK)

All chunk types are supported: text, reasoning, tool call (start/delta/result), source, file, data, error, finish message/step.

Requirements

• OCaml >= 4.14
• For Melange bindings: melange >= 4.0.0

Development

make build    # Build all libraries
make test     # Run test suites
make dev      # Watch mode

License

MIT