The Wyn Language Specification

Introduction

Wyn is a minimal functional programming language designed for GPU shader programming. It generates SPIR-V code for use with modern graphics APIs like Vulkan and WebGPU. The language draws inspiration from Futhark’s array-oriented programming model while maintaining simplicity and focusing specifically on shader development.

Design Goals

• Shader-focused: Designed specifically for vertex, fragment, and compute shader programming
• Array-oriented: First-class support for multi-dimensional arrays and array operations
• Type-safe: Static type checking with explicit type annotations
• SPIR-V target: Direct compilation to SPIR-V for maximum compatibility
• Functional: Immutable data structures and expression-based computation
• Minimal: Small, focused language with essential features for shader development

Key Features

• Multi-dimensional array types with literal syntax
• Built-in functions for array-to-vector conversion (SPIR-V compatibility)
• Entry point declarations for vertex and fragment shaders
• Automatic semantic mapping (e.g., [4]f32 → gl_Position for vertex shaders)
• Static type checking with type inference
• Integration with GPU built-in variables (gl_VertexIndex, etc.)

Language Overview

Wyn programs consist of:

• Global declarations: Constants and arrays defined with let or def
• Built-in function signatures: Polymorphic functions defined with val
• Shader entry points: entry declarations with #[vertex], #[fragment], or #[compute] attributes