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Language Specification

This page will contain the full Sailfin language specification. The canonical source is docs/spec.md in the Sailfin repository.

The specification is organized in two parts:

Part A — Current Language

What ships and works today in the self-hosted native compiler:

  • Lexical Structure — Identifiers, keywords, literals, comments
  • Modules & Imports — Module system and capability imports
  • Declarations — Variables, functions, structs, interfaces, enums, type aliases, models, prompts, pipelines, tools
  • Statements & Control Flow — If/else, match, try/catch, loops, for-in
  • Concurrency — Async/await, routines, channels, accelerators
  • Type System — Primitives, composites, vectors, tensors, wrapper types (PII, Secret, Affine, Linear)
  • Ownership & Borrowing — Move semantics, shared/mutable references, unsafe FFI, raw pointers
  • Capability-Based Security — Effect annotations, intrinsic declarations, transitive enforcement
  • String Interpolation — {{ expression }} syntax
  • Runtime Semantics — Prelude, printing, logging, string utilities
  • Testing — Test declarations, evaluators, replay

Part B — Design Preview

Features that are specified but not yet fully implemented:

  • Native backend layout descriptors
  • Hierarchical effect system
  • Pipeline operator (|>)
  • Currency literals

Full specification content will be published here as part of the 1.0 documentation effort. For now, refer to the source spec.