Language Specification

This is the authoritative web reference for the Sailfin language as implemented by the self-hosted native compiler. It covers syntax, semantics, the type system, the effect system, and the runtime contract.

The specification is split across chapters for readability:

• §1 Lexical Structure
• §2 Modules and Imports
• §3 Declarations
• §4 Statements and Control Flow
• §5 Expressions and Operators
• §6 Type System
• §7 Effect System
• §8 Pattern Matching
• §9 String Interpolation
• §10 Runtime
• §11 Testing

For planned-but-not-yet-shipped features, see the Design Preview.

The canonical source is this site; the markdown chapter files live under site/src/content/docs/docs/reference/spec/ in the repository.