Dryad

A modern dynamic programming language with a self-hosting standard library and a minimal C++ runtime.

Dryad keeps the runtime small by exposing a tiny set of intrinsic syscalls (~50) that the standard library — written 100% in Dryad — builds on. No manual bindings, no wrapper layers: the language implements itself.

Status

Early implementation. The C++ interpreter (Phase 0–3) is functional, the standard library is growing (Buffer plus VFS I/O), and the test suite covers 454 tests (435 unit + 19 integration) on Linux. The CLI runs .dryad scripts with import support (dryad script.dryad); REPL is not implemented yet. See CHANGELOG and the phase reports under src/ for details.

Architecture

Layer 4: Application Code (user Dryad programs)
   ↓
Layer 3: Standard Library (100% Dryad)
   @std/core, @std/io, @std/buffers
   ↓
Layer 2: Intrinsics Layer (~50 syscall primitives)
   file I/O, memory, strings, process, network
   ↓
Layer 1: C++ Micro-Kernel Runtime
   interpreter, GC, module loader, environment

• Self-hosting: the standard library is written in Dryad and only talks to the runtime through intrinsics.
• Minimal runtime: ~50 intrinsic syscalls instead of hundreds of hand-maintained native bindings.
• Error model: stdlib errors are values (strings from @std/core/exceptions), never exceptions thrown across the language boundary.

Repository layout

The project is split into two repositories, assembled as modules:

Path	Repository	Contents
src/	source (this repo)	C++ interpreter, standard library, tests
docs/	dryadlang/docs	Documentation, examples, language specification
CHANGELOG	source	Notable changes per release

docs/ is registered as a git submodule, so a full checkout is:

git clone --recurse-submodules https://gitlab.com/dryadlang/source.git

Building

Requirements: C++17 compiler (MSVC or GCC/Clang with MSYS2), CMake 3.15+.

cmake -S src -B src/build -DCMAKE_BUILD_TYPE=Release
cmake --build src/build

The dryad binary is produced at src/build/bin/dryad.

Testing

cd src/build
ctest --output-on-failure

Or run a single test binary directly:

./bin/unit_tests         # unit tests (lexer, parser, interpreter, intrinsics, buffers, ...)
./bin/integration_tests  # end-to-end workflows (buffer roundtrips, file I/O, example scripts)

Tests are built with -Wall -Wextra -Werror.

Example

docs/examples/02-buffers/buffer_usage.dryad — UTF-8 string ↔ buffer conversion, slicing, and byte editing:

let text = "Olá, mundo!";
let buf = Buffer_FromString(text);
let ok = Buffer_AsString(buf) == text;

let slice = Buffer_Slice(buf, 0, 4);
ok = ok && (Buffer_AsString(slice) == "Olá");
Buffer_Dispose(slice);

Buffer_Write(buf, 0, 88);              // 'X'
ok = ok && (Buffer_AsString(buf) == "Xlá, mundo!");

Buffer_Dispose(buf);

Run examples with the CLI:

src/build/bin/dryad docs/examples/02-buffers/buffer_usage.dryad
src/build/bin/dryad docs/examples/04-io/file_io_usage.dryad
src/build/bin/dryad docs/examples/04-io/io_examples.dryad

# Run all examples with timing
./docs/examples/run_benchmark.sh

Set DRYAD_STDLIB_DIR if the stdlib is not at the default install path.

Documentation

All documentation is consolidated under docs/. Full inventory: docs/SITEMAP.md.

Section	Path
Quick start	docs/getting-started/quick-start.md
Language reference	docs/language/
Specification (PDF)	docs/specification/theory/
Standard library	docs/stdlib/
User libraries	docs/libraries/
CLI & tooling	docs/tooling/
Implementation	docs/implementation/
Diagrams (PlantUML)	docs/diagrams/
Examples	docs/examples/README.md

Contributing

See CONTRIBUTING.md. In short: tests come first (TDD), commits are small and focused, and the whole suite must stay green. Documentation contributions go to the docs module repository.

License

MIT — Copyright (c) 2026 Pedro Kaleb.