A Python library for parallel LLM inference across providers, built on Polars DataFrames.
Polar Llama is a Python library that enables parallel inference calls to multiple Large Language Model providers through Polars dataframes. It streamlines batch processing of AI queries without serial request delays, making it ideal for data-intensive AI applications. 0.6.0 opens a run of production-hardening releases with token-by-token streaming via inference_stream(), still returned as an ordinary DataFrame column.
Send multiple inference requests in parallel without waiting for individual completions
OpenAI, Anthropic, Gemini, Groq, AWS Bedrock, and on-device MLX (Apple Silicon)
Dataframe-native tool calling: emission, batch-parallel execution, and synthesis are all ordinary columns
Built for long batch jobs: token streaming
Pulls in mlx and mlx-lm; requires an Apple Silicon Mac and Python ≥ 3.10
Get started with a simple example
inference_stream(): token-by-token deltas via an on_token callback, still returned as a column (#74)
inference_stream() streams completions token-by-token through an on_token(row_index, delta) callback, and still returns an ordinary DataFrame column, so there is no separate iterator to manage. Each row is a Struct{text: Utf8, finished: Boolean} (exported as STREAM_RESPONSE_DTYPE), so the frame stays rectangular even when a stream is cut off.
| Provider | Transport |
|---|---|
| OpenAI | Native SSE |
| Groq | Native SSE (OpenAI-compatible) |
| Anthropic | Native SSE |
| Gemini | Buffered fallback: one full-text delta, then completion |
| AWS Bedrock | Buffered fallback: one full-text delta, then completion |
Streaming is text-only: passing response_model or response_format raises a ValueError immediately, so use inference_async() for structured output. Pass messages=True to stream JSON-encoded message arrays instead of bare user strings. Also available as pl.col("prompt").llama.inference_stream(...).
finished=False plus a RuntimeWarning, never a broken DataFrame
finished=True means the stream reached a clean terminator ([DONE] for OpenAI and Groq, message_stop for Anthropic, or the buffered fallback). finished=False covers every other outcome: a mid-stream provider error event, a transport drop, EOF without a completion marker, an on_token callback that raises, or Ctrl-C. Each one is reported as a RuntimeWarning with whatever partial text had arrived. No exception propagates out of the expression, including KeyboardInterrupt, so the DataFrame’s height and schema are always intact.
row_index is the index within the batch the call executes. It equals the column index under the default collect() engine, but may restart from 0 per batch under the streaming engine.
Point the Groq client at a proxy, gateway, or local mock server
GROQ_BASE_URL now overrides the Groq endpoint, matching the existing OPENAI_BASE_URL / ANTHROPIC_BASE_URL pattern. The streaming tests also use it to point Groq at a local mock server. Under the hood, reqwest’s stream feature is now enabled for chunked body streaming in the new SSE drivers.
0.6.0 is cumulative: every feature shipped in 0.2.2 is still here, plus everything added across 0.3.0, 0.5.0, 0.5.1, 0.5.2, 0.5.3.
Released 2026-06-10 to 2026-07-12
tools_to_response_model, mcp_tools, execute_tool_calls, tool_results_to_message: batch-parallel tool calling over an MCP server or a Python executor (0.3.0)
cache=True / CacheConfig shares a cached system prefix across rows via Anthropic cache_control, with 5-minute and 1-hour TTLs (0.3.0)
Signature, Predict, evaluate, BootstrapFewShot, InstructionOptimizer: DSPy-style instruction and few-shot tuning (0.3.0)
inference_local with server and in_process engines, collapsed prefix prefill, batched quantized KV cache (0.5.0), and an on-device prompt-tuning bridge (0.5.1)
Along the way: updated default models for every provider, OPENAI_BASE_URL / ANTHROPIC_BASE_URL overrides and POLAR_LLAMA_MAX_CONCURRENCY (0.3.0), and fixes for in-process Gemma 3n inference (0.5.2). See the 0.5.2 docs for the full details.
Released 2026-07-13
tag_taxonomy() works on OpenAI strict mode again. The per-field thinking reasoning is now List[{value, reasoning}] instead of a dict keyed by value name, and $ref sibling keywords are stripped from generated schemas (#51). A new warning flags Dict-typed fields in user-supplied response models.
The agent loop unrolled into ordinary dataframe columns
Declare a task, then let an optimizer tune instructions or mine few-shot demos
Batched generation via mlx-lm, no API keys, no network
Process customer feedback at scale
Generate embeddings, then find nearest neighbors with HNSW
Classify documents with reasoning, reflection, and confidence scores
Six inference targets: five hosted providers plus on-device MLX
Default model: gpt-4o-mini
Default model: claude-opus-4-8; supports cache=True for prompt caching
Default model: us.anthropic.claude-haiku-4-5-20251001-v1:0; region resolved from AWS_REGION / AWS_DEFAULT_REGION
Default model: gemini-2.5-flash; native system_instruction and JSON-schema structured outputs
Default model: llama-3.3-70b-versatile; GROQ_BASE_URL overrides the endpoint (0.6.0+)
No API key, no network: the server engine points at a local OpenAI-compatible endpoint, and in_process drives mlx-lm directly
Core expressions exported from polar_llama
| Function | Purpose |
|---|---|
| inference_async(expr, *, provider, model, response_model, cache, system_prompt) | Parallel async inference; accepts cache=True/CacheConfig and system_prompt for provider-native prompt caching |
| inference(expr, *, provider, model, response_model) | Synchronous inference (deprecated in favor of inference_async) |
| inference_messages(expr, *, provider, model, response_model, cache) | Multi-turn conversation inference over JSON or List(Struct) message arrays |
| inference_stream(expr, *, provider, model, on_token, messages) | Token-by-token streaming; returns Struct{text, finished} per row |
| string_to_message(expr, *, message_type) | Convert text to a {role, content} message |
| combine_messages(*exprs) | Merge message columns/arrays into one ordered conversation |
| tag_taxonomy(expr, taxonomy, *, provider, model) | Classify text against a taxonomy with reasoning, reflection, and confidence |
| embedding_async(expr, *, provider, model) | Parallel embedding generation (OpenAI, Gemini, Bedrock) |
| cosine_similarity / dot_product / euclidean_distance(vec1, vec2) | Rust-powered vector similarity metrics |
| knn_hnsw(query_expr, reference_expr, *, k) | Stateless approximate nearest-neighbor search via HNSW |
| mcp_tools(transport, *, timeout_s) | Fetch tool definitions from an MCP server (tools/list) |
| tools_to_response_model(tools, *, model_name) | Build a Pydantic emission schema so the LLM emits structured tool calls |
| execute_tool_calls(expr, *, transport, executor, tools, concurrency, timeout_s) | Run every emitted call of every row in parallel; failures are data |
| tool_results_to_message(expr, *, role) | Render tool results as a message for the synthesis inference pass |
| Signature / Predict / evaluate / BootstrapFewShot / InstructionOptimizer | DSPy-style prompt optimization engine (polar_llama.optimize) |
| col(...).llama.inference_local(*, model, system, engine, base_url, max_tokens, temperature, top_p, stop) | On-device inference on Apple Silicon via mlx-lm |
| polar_llama.local.make_local_inference_fn(model, *, engine, collapse, max_tokens, ...) | Build an inference_fn that backs the optimizer with on-device Gemma 3n |
Every expression is also available on the fluent .llama namespace (pl.col("text").llama.inference_async(...), .llama.to_message(...), .llama.embedding(...), .llama.inference_stream(...), and so on).
Set up your API keys and overrides in a .env file:
Share a cached system prefix across rows (Anthropic cache_control):
Run tests with configured providers:
Process large datasets with AI insights: sentiment analysis, classification, entity extraction with validated structured outputs
Let the LLM call databases, internal APIs, or MCP servers at scale, with every call, result, and retry as an ordinary dataframe column
Run classification, extraction, or tuning on local models with no API keys and no data leaving the machine
Bootstrap few-shot demos or search for better instructions against a labeled dataset, entirely offline or on-device
Licensed under MIT.
Questions or issues? Open one on GitHub.