Changelog

v0.3.3 March 9, 2026

New native List and String operations, a refinement checker fix, and benchmark validation proving Baseline beats Python on all seven Hanabi benchmarks.

Standard Library

• List.count_flips -- pancake flip loop executed entirely in Rust with in-place mutation
• List.rotate_left, List.reverse_prefix, List.swap -- permutation primitives with CoW owning variants
• List.push -- single-element append with copy-on-write
• List.bisect -- linear scan for cumulative probability threshold
• String.cyclic_substring -- extract chars with wrap-around, fast ASCII byte path
• String.random_fasta_line -- PRNG loop with cumulative lookup and string building in one native call

Bug Fixes

• Fixed refinement checker parsing of string equality with || operator
• Refined String ++ operator support

Benchmarks

• Baseline now beats Python on all 7 Hanabi benchmarks (nbody, binarytrees, fasta, fannkuch-redux, spectral-norm, pidigits, mandelbrot)
• Added optimized benchmark programs and multi-language comparison harness

v0.3.2 March 9, 2026

Production-ready server runtime, scalar replacement of aggregates, and mutable bindings. The HTTP server gains middleware, graceful shutdown, rate limiting, compression, and CORS -- while the JIT compiler delivers major performance wins through SRA and scalar RC elision.

Server

• JIT-compiled middleware chain with next(req) continuation
• Graceful shutdown on SIGINT/SIGTERM with 30s connection drain
• Per-IP rate limiting (token bucket, 100 req/s) with 429 responses
• Gzip response compression for bodies over 1KB
• Built-in CORS preflight handling for OPTIONS requests
• Request header (8KB) and body (1MB) size limits with 413 responses
• Structured request logging with request ID tracking
• Built-in /__health endpoint
• Keep-alive timeout (30s) and server workers via SO_REUSEPORT
• Panic recovery with catch_unwind around handler dispatch

JIT Compiler

• Scalar replacement of aggregates (SRA) -- record parameters decomposed into individual registers, eliminating heap allocation in tight loops
• SRA let-floating exposes inlined records to optimization (6x nbody speedup)
• Scalar RC elision -- skip incref/decref for Int, Float, Bool, Unit values
• Multi-value returns for all-scalar records (one register per field)
• Mutable field assignment compiles to direct SRA variable update (zero allocation)
• Tail recursion modulo constructor (TRMC) rewrites recursive constructors into iterative loops
• Typed drop-reuse codegen for enum, tuple, record, and struct values
• Typed JitError variants and can_jit_reason() diagnostics
• Profiling counters via BLC_JIT_COUNTERS and IR dump via BASELINE_DUMP_IR

Language

• let mut bindings with assignment statements for mutable local variables
• Mutable record field assignment (obj.field = val)

Tooling

• Moved to baseline-lang GitHub organization
• Heap benchmark gate and nbody reference outputs in CI

v0.3.0 March 5, 2026

JIT-only execution, fiber-based effect handlers, and a major stdlib expansion. The tree-walk interpreter has been removed -- Cranelift JIT is now the default and only runtime.

JIT Compiler

• Cranelift JIT is now the default and only runtime -- the bytecode VM interpreter has been removed
• Self-tail-call optimization (recursive calls compile to loops)
• Base-case speculation inlines guard checks at call sites
• Clone-on-write enum field updates bypass Arc::get_mut via safe raw pointer mutation
• Owning dispatch for native CoW functions
• Evidence passing transform for tail-resumptive effects
• Float arithmetic (+, -, *, /) in native code
• List pattern matching in JIT
• Error propagation replaces panics with catch_unwind

Performance

• Indexed field access -- field indices resolved at compile time, O(1) Vec lookup at runtime
• Aggressive function inlining (lightweight functions up to 120 IR nodes)
• Tuple-let fusion eliminates allocation from inlined multi-return
• Non-atomic RC mode for single-threaded execution
• Checked integer overflow replaces silent wrapping arithmetic
• Persistent map operations optimized
• Unboxed scalar fast path restored for non-Int scalar functions

Effects & Handlers

• Fiber-based effect handlers with Perceus reuse analysis
• One-shot continuation semantics codified
• JIT effect conformance tests
• Arithmetic on refined types

Standard Library

• Math.sqrt, Math.sin, Math.cos, Math.atan2, Math.floor, Math.ceil
• Float.from_int, Float.format, Int.from_float
• Map.map, Map.filter, Map.fold, Map.entries
• List.set, List.slice, List.fill, List.get_or
• Implicit first-arg piping
• 17 new API modules, 135 new functions total

Tooling

• GitHub Actions release workflow with Homebrew-compatible tarballs
• Conformance regression gates in CI
• Package dependency resolution
• Async LSP improvements
• Language tour for new developers
• Error message catalog with all 56 diagnostic codes

v0.2.0 February 17, 2026

Web framework, database connectors, trait system, and advanced pattern matching. This release turns Baseline into a practical language for building web services.

Web Framework

• Router module with route definitions, Router.resources, and Router.state
• Request module with typed parameter extraction
• Response helpers with auto-serialization
• Middleware module for request/response pipelines
• Server runtime with router state injection and auto-docs
• HttpError expanded to 12 variants with JSON:API error format
• Structured error pipelines, multipart parsing, JWT auth, in-memory sessions
• WebSocket support and schema-driven validation

Database

• Generic SQL backend with Sqlite, Postgres, and Mysql connectors
• Typed database rows with SqlValue, Row, and typed accessors
• query_map! HOF and query_one! for all backends
• Parameterized queries and migration runner

Type System

• Trait/interface system with compile-time dictionary-passing dispatch
• Record destructuring and open records with row polymorphism
• Trait bounds with supertrait support

Pattern Matching

• Guard patterns (match x { n if n > 0 => ... })
• Or-patterns (match x { 1 | 2 | 3 => ... })
• List patterns (match xs { [head, ..tail] => ... })
• Enhanced record patterns with partial matching and literal fields

Standard Library

• Crypto, DateTime, Regex modules
• Result.map_err and Result.context for error conversions
• Semantic logger with timestamps, structured fields, and JSON output
• Unified Log API (removed _with! variants)
• Validate module

Tooling

• MCP server with 5 tools for AI agent integration
• Website redesign with API reference, guides, and search
• llms.txt and llms-full.txt for AI agent context
• blc docs CLI search and expanded API documentation
• Rosetta Stone and Common Agent Mistakes in llms.txt

v0.1.0 February 2, 2026

Initial release. A working compiler with type checking, effect inference, refinement types, and an interpreter runtime.

Language

• Core types: Int, String, Boolean, Float, List<T>
• Sum types with Option<T> and Result<T, E>
• Closures, string interpolation, tuple evaluation
• Pattern matching with match expressions
• Pipe operator (|>), range expressions (1..10)
• Module system with @prelude levels

Type System

• Hindley-Milner-style inference for built-in generics
• Effect inference with transitive checking via call graph
• Refinement types with integer interval constraints (type Port = Int where self > 0)
• Built-in effects: Console, Http, Fs, Log, Time, Random, Env

Standard Library

• Math module with arithmetic and comparison functions
• String module with manipulation and search
• List module with map, filter, fold, find, head, tail
• Option and Result modules with constructors and combinators

Tooling

• Tree-sitter parser (tree-sitter-baseline)
• blc check with JSON diagnostic output
• Zed editor extension with syntax highlighting
• Property-based tests and fuzzing targets
• Conformance test suite (45 test files, 12 categories)