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Donner (Kotlin)

Kotlin JVM bytecode compiler with Java interop

Repository: eddmann/santa-lang-donner Version: 1.0.3

Overview

Donner compiles santa-lang directly to JVM bytecode using the ASM library. Programs are compiled to Java .class files that run on any Java 21+ runtime, benefiting from JVM optimizations and JIT compilation.

The implementation uses persistent data structures throughout and includes full support for the AoC runner with test blocks and memoization. Uniquely, Donner provides Java interop functions for seamless integration with the Java ecosystem.

Downloads

CLI

Platform Download
Linux (x64) santa-lang-donner-cli-1.0.3-linux-amd64.tar.gz
macOS (Intel) santa-lang-donner-cli-1.0.3-macos-amd64.tar.gz
macOS (ARM) santa-lang-donner-cli-1.0.3-macos-arm64.tar.gz
JAR santa-lang-donner-cli-1.0.3.jar
Docker docker pull ghcr.io/eddmann/santa-lang-donner:cli-latest

Installation

docker run --rm ghcr.io/eddmann/santa-lang-donner:cli-latest -e '1 + 1'

Binary Download

# Download and extract for your platform
curl -L https://github.com/eddmann/santa-lang-donner/releases/download/1.0.3/santa-lang-donner-cli-1.0.3-macos-arm64.tar.gz | tar xz
./santa-cli --help

JAR (Requires Java 21+)

curl -L -o santa-cli.jar https://github.com/eddmann/santa-lang-donner/releases/download/1.0.3/santa-lang-donner-cli-1.0.3.jar
java -jar santa-cli.jar --help

Supported Runtimes

Architecture

Source Code → Lexer → Parser → Desugar → Resolver → Bytecode Gen (ASM) → JVM
                                                          │
                                                    In-Memory Classes
                                                    (ScriptClassLoader)

Donner uses a multi-stage compilation pipeline:

  1. Lexer - Tokenization with position tracking
  2. Parser - Pratt parser producing an AST
  3. Desugaring - Three passes: placeholder (_), pipeline (|>), pattern parameters
  4. Resolver - Two-pass scope resolution with forward reference support
  5. Bytecode Generation - JVM bytecode via ASM 9.7

Desugaring Passes

Pass Transformation
PlaceholderDesugarer _ + 1 → \|$0\| $0 + 1
PipelineDesugarer a \|> f → f(a)
PatternParamDesugarer \|[a, b]\| ... → \|$p\| let [a, b] = $p; ...

In-Memory Compilation

Donner compiles directly to in-memory .class files without touching the filesystem:

CompiledScript {
    mainClass: ByteArray,          // Main script class
    lambdaClasses: Map<String, ByteArray>  // Lambda inner classes
}

A custom ScriptClassLoader loads these classes for execution.

Value System

All runtime values implement a sealed Value interface:

Type Backing Implementation
IntValue Long
DecimalValue Double
StringValue String (grapheme-cluster indexed)
BoolValue Boolean
NilValue Singleton
ListValue kotlinx.collections.immutable.PersistentList
SetValue kotlinx.collections.immutable.PersistentSet
DictValue kotlinx.collections.immutable.PersistentMap
FunctionValue Compiled lambda class

Java Interop

Donner includes functions for seamless Java integration:

Function Description
require(className) Load a Java class by name
java_new(class, ...args) Create instance with constructor
java_call(object, method, ...args) Call instance method
java_static(class, method, ...args) Call static method
method(name) Create method reference for pipelines
static_method(class, name) Create static method reference

Example: Java Interop

let ArrayList = require("java.util.ArrayList");
let list = java_new(ArrayList);
java_call(list, "add", "hello");
java_call(list, "add", "world");
java_call(list, "size") // => 2

// Pipeline-friendly methods
let StringBuilder = require("java.lang.StringBuilder");
java_new(StringBuilder)
  |> method("append")("Hello, ")
  |> method("append")("World!")
  |> method("toString")
  // => "Hello, World!"

Type Conversion

Values are automatically converted between santa-lang and Java:

santa-lang Java
Integer Long / Integer
Decimal Double
String String
Boolean Boolean
List List<?>
Dict Map<?, ?>
Nil null

CLI Usage

Requires Java 21+.

# Run a solution
santa-cli solution.santa

# Run with tests
santa-cli -t solution.santa

Building from Source

Requires Java 21+ and Gradle.

git clone https://github.com/eddmann/santa-lang-donner.git
cd santa-lang-donner
make build      # Build CLI
make test       # Run tests
make cli/jar    # Build fat JAR

See Also