The Turn Book

Why Turn

The five failure modes of every agent framework, and how Turn solves them at the language level.

Installation

Install the Turn binary, configure an inference provider, and run your first intelligent program.

Hello Turn

A step-by-step trace of your first Turn program: env, memory, context, call, and return.

Grammar

Formal syntax: statements, expressions, blocks, and type annotations.

Types and Errors

Every type in Turn: Num, Str, Bool, Struct, List, Map, Pid, Vec, Identity, and Uncertain.

Error Handling

Structured error handling with try/catch/throw and actor-level fault propagation via spawn_link.

Modules

Import local files, HTTPS URLs, API schemas, and WebAssembly binaries with use.

Standard Library

Seven pure Turn modules for networking, filesystem, JSON, time, environment, regex, and math.

Runtime Model

VM execution model, actor scheduler, suspension and resumption, and durable state.

State & Persistence

How Turn agents achieve durable state using remember/recall, struct spread, and execution suspension.

Concurrency and Actors

spawn, spawn_link, spawn_each, send, receive, and self: Erlang-style actors for agent orchestration.

Budget Guardrails

The VM gas meter that bounds every process by construction, preventing runaway agents and surprise API bills.

The infer Primitive

Cognitive Type Safety: how infer generates schemas at compile time and validates LLM output.

The decide Primitive

Bounded Choice, Score, and Noul judgments through decision-model providers such as TypeSafe Jev.

Struct Inference

The simplest demonstration of Cognitive Type Safety: infer populates a strictly typed struct at runtime.

Probabilistic Routing

Confidence thresholds and deterministic fallbacks for stochastic inference results.

Context Window

Per-process context window management with context.append and context.system.

Memory & Recall

Persistent key-value memory across sessions and restarts using remember and recall.

Inference Providers

The Wasm sandbox architecture, official providers, and how to write your own driver.

Zero-Trust Identity

How Turn's grant identity primitive prevents LLM agents from ever seeing raw API credentials.

Ecosystem Bridges

Using Wasm components, schema absorption, and infer Struct for external system integration.

Boardroom Agent

A full multi-agent boardroom simulation with live data, actor coordination, and confidence gating.

Investment Committee

Three specialist agents evaluate a live NVDA equity position using Yahoo Finance data.

Marketing Agency

SEO, Copywriter, and Creative Director agents collaborate to generate high-converting ad copy.

Algorithmic Trading Syndicate

A concurrent multi-agent quantitative hedge fund. Technical, Sentiment, and Chairman agents debate an asset and produce a trade signal.

Web Search Agent

An autonomous web search agent combining Wikipedia inference, concurrent HTTP, and stochastic context synthesis.

Persistent Agent

Shows how remember and recall survive process restarts, incrementing state across runs.

Quick Reference

A cheat sheet for Turn's core primitives, syntax, built-in tools, and standard library.

Design Mandate

The philosophy, constraints, and design principles locked into the Turn language.

Implementation

Compiler pipeline, schema compiler, bytecode instruction set, and VM internals.

LSP

Language Server Protocol integration and editor support.