Compiler Architecture

Pipeline

The compiler follows a multi-stage pipeline:

Source (.sfn)
  → Lexer (lexer.sfn) → Tokens
  → Parser (parser.sfn) → AST (ast.sfn)
  → Type Checker (typecheck.sfn) → Validated AST
  → Effect Checker (effect_checker.sfn) → Effect-safe AST
  → Native Emitter (emit_native.sfn) → .sfn-asm IR (native_ir.sfn)
  → LLVM Lowering (llvm/lowering/) → LLVM IR
  → LLVM → Native Binary

Key Files

File	Role
`compiler/src/main.sfn`	Entry point, orchestrates all passes
`compiler/src/lexer.sfn`	Tokenizer
`compiler/src/parser.sfn`	Parser → AST
`compiler/src/ast.sfn`	AST node definitions
`compiler/src/typecheck.sfn`	Type checking, interface conformance
`compiler/src/effect_checker.sfn`	Effect validation
`compiler/src/emit_native.sfn`	Emit `.sfn-asm` IR
`compiler/src/native_ir.sfn`	IR representation
`compiler/src/llvm/lowering/entrypoints.sfn`	LLVM IR generation

Runtime

The runtime currently ships as C under runtime/native/ and is planned to migrate to Sailfin before 1.0.

runtime/prelude.sfn — Sailfin-native prelude (collections, strings, type checks)
runtime/native/ — C runtime implementation

Self-Hosting

The compiler compiles itself. The build process:

A seed binary (a previously compiled version) bootstraps the build
The seed compiles the current source into a first-pass binary
The first-pass binary compiles the source again into the seedcheck binary
make check validates the seedcheck can run programs and pass tests

Intermediate Representation

.sfn-asm is a textual IR that sits between the AST and LLVM IR. It represents:

Function declarations and bodies
Basic blocks and control flow
Type metadata
Effect annotations

For details on the LLVM lowering passes, see compiler/src/llvm/lowering/.