chore: Use actors

15 files changed, 499 insertions, 499 deletions

diff --git a/core/src/main/java/coffee/liz/lambda/LambdaDriver.java b/core/src/main/java/coffee/liz/lambda/LambdaDriver.java
index 2ba8c70..59cee25 100644
--- a/core/src/main/java/coffee/liz/lambda/LambdaDriver.java
+++ b/core/src/main/java/coffee/liz/lambda/LambdaDriver.java
@@ -20,60 +20,60 @@ import java.util.List;
  */
 public class LambdaDriver {
 
-	/**
-	 * Parses source code into an AST.
-	 *
-	 * @param sourceCode
-	 *            the source code (either Lambda or Arrow syntax)
-	 * @return the parsed program
-	 */
-	public static LambdaProgram parse(final SourceCode sourceCode) {
-		return switch (sourceCode) {
-			case SourceCode.Lambda(String source) -> parseLambda(source);
-			case SourceCode.Arrow(String source) -> parseArrow(source);
-		};
-	}
+    /**
+     * Parses source code into an AST.
+     *
+     * @param sourceCode
+     *            the source code (either Lambda or Arrow syntax)
+     * @return the parsed program
+     */
+    public static LambdaProgram parse(final SourceCode sourceCode) {
+        return switch (sourceCode) {
+            case SourceCode.Lambda(String source) -> parseLambda(source);
+            case SourceCode.Arrow(String source) -> parseArrow(source);
+        };
+    }
 
-	private static LambdaProgram parseLambda(final String source) {
-		try (final StringReader reader = new StringReader(source)) {
-			return new LambdaParser(reader).Program();
-		} catch (final ParseException parseException) {
-			throw new RuntimeException("Failed to parse program", parseException);
-		}
-	}
+    private static LambdaProgram parseLambda(final String source) {
+        try (final StringReader reader = new StringReader(source)) {
+            return new LambdaParser(reader).Program();
+        } catch (final ParseException parseException) {
+            throw new RuntimeException("Failed to parse program", parseException);
+        }
+    }
 
-	private static LambdaProgram parseArrow(final String source) {
-		try (final StringReader reader = new StringReader(source)) {
-			return new ArrowParser(reader).Program();
-		} catch (final ParseException parseException) {
-			throw new RuntimeException("Failed to parse program", parseException);
-		}
-	}
+    private static LambdaProgram parseArrow(final String source) {
+        try (final StringReader reader = new StringReader(source)) {
+            return new ArrowParser(reader).Program();
+        } catch (final ParseException parseException) {
+            throw new RuntimeException("Failed to parse program", parseException);
+        }
+    }
 
-	/**
-	 * Parses and evaluates lambda calculus programs.
-	 *
-	 * @param sourceCode
-	 *            the source code
-	 * @return the evaluated result
-	 */
-	public static Value interpret(final SourceCode sourceCode) {
-		return interpret(sourceCode, List.of());
-	}
+    /**
+     * Parses and evaluates lambda calculus programs.
+     *
+     * @param sourceCode
+     *            the source code
+     * @return the evaluated result
+     */
+    public static Value interpret(final SourceCode sourceCode) {
+        return interpret(sourceCode, List.of());
+    }
 
-	/**
-	 * Parses and evaluates lambda calculus programs with "FFI"'s.
-	 *
-	 * @param sourceCode
-	 *            the source code
-	 * @param bindings
-	 *            external Java functions available during evaluation
-	 * @return the evaluated result
-	 */
-	public static Value interpret(final SourceCode sourceCode, final List<ExternalBinding> bindings) {
-		final LambdaProgram program = parse(sourceCode);
-		final Expression expression = program.expression();
-		final List<Macro> macros = program.macros();
-		return NormalOrderEvaluator.evaluate(expression, Environment.from(macros, bindings));
-	}
+    /**
+     * Parses and evaluates lambda calculus programs with "FFI"'s.
+     *
+     * @param sourceCode
+     *            the source code
+     * @param bindings
+     *            external Java functions available during evaluation
+     * @return the evaluated result
+     */
+    public static Value interpret(final SourceCode sourceCode, final List<ExternalBinding> bindings) {
+        final LambdaProgram program = parse(sourceCode);
+        final Expression expression = program.expression();
+        final List<Macro> macros = program.macros();
+        return NormalOrderEvaluator.evaluate(expression, Environment.from(macros, bindings));
+    }
 }
diff --git a/core/src/main/java/coffee/liz/lambda/ast/Expression.java b/core/src/main/java/coffee/liz/lambda/ast/Expression.java
index 6d75a08..c2bdd39 100644
--- a/core/src/main/java/coffee/liz/lambda/ast/Expression.java
+++ b/core/src/main/java/coffee/liz/lambda/ast/Expression.java
@@ -8,21 +8,21 @@ import java.util.Optional;
  * Represents an expression in the untyped lambda calculus.
  */
 public sealed interface Expression
-		permits Expression.AbstractionExpression, Expression.IdentifierExpression, Expression.ApplicationExpression {
+        permits Expression.AbstractionExpression, Expression.IdentifierExpression, Expression.ApplicationExpression {
 
-	Optional<SourceComment> comment();
+    Optional<SourceComment> comment();
 
-	SourceSpan span();
+    SourceSpan span();
 
-	record AbstractionExpression(@NonNull Optional<SourceComment> comment, @NonNull SourceSpan span,
-			@NonNull String parameter, @NonNull Expression body) implements Expression {
-	}
+    record AbstractionExpression(@NonNull Optional<SourceComment> comment, @NonNull SourceSpan span,
+            @NonNull String parameter, @NonNull Expression body) implements Expression {
+    }
 
-	record ApplicationExpression(@NonNull Optional<SourceComment> comment, @NonNull SourceSpan span,
-			@NonNull Expression applicable, @NonNull Expression argument) implements Expression {
-	}
+    record ApplicationExpression(@NonNull Optional<SourceComment> comment, @NonNull SourceSpan span,
+            @NonNull Expression applicable, @NonNull Expression argument) implements Expression {
+    }
 
-	record IdentifierExpression(@NonNull Optional<SourceComment> comment, @NonNull SourceSpan span,
-			@NonNull String name) implements Expression {
-	}
+    record IdentifierExpression(@NonNull Optional<SourceComment> comment, @NonNull SourceSpan span,
+            @NonNull String name) implements Expression {
+    }
 }
diff --git a/core/src/main/java/coffee/liz/lambda/ast/Macro.java b/core/src/main/java/coffee/liz/lambda/ast/Macro.java
index 07ba911..4a485fc 100644
--- a/core/src/main/java/coffee/liz/lambda/ast/Macro.java
+++ b/core/src/main/java/coffee/liz/lambda/ast/Macro.java
@@ -8,5 +8,5 @@ import java.util.Optional;
  * A named macro definition that maps an identifier to an expression.
  */
 public record Macro(@NonNull Optional<SourceComment> comment, @NonNull SourceSpan span, @NonNull String name,
-		@NonNull Expression expression) {
+        @NonNull Expression expression) {
 }
diff --git a/core/src/main/java/coffee/liz/lambda/ast/SourceCode.java b/core/src/main/java/coffee/liz/lambda/ast/SourceCode.java
index 200c45e..c2112ad 100644
--- a/core/src/main/java/coffee/liz/lambda/ast/SourceCode.java
+++ b/core/src/main/java/coffee/liz/lambda/ast/SourceCode.java
@@ -4,24 +4,24 @@ package coffee.liz.lambda.ast;
  * Represents source code in one of the supported lambda calculus syntaxes.
  */
 public sealed interface SourceCode {
-	static SourceCode ofLambda(final String source) {
-		return new Lambda(source);
-	}
+    static SourceCode ofLambda(final String source) {
+        return new Lambda(source);
+    }
 
-	static SourceCode ofArrow(final String source) {
-		return new Arrow(source);
-	}
+    static SourceCode ofArrow(final String source) {
+        return new Arrow(source);
+    }
 
-	record Lambda(String source) implements SourceCode {
-	}
+    record Lambda(String source) implements SourceCode {
+    }
 
-	record Arrow(String source) implements SourceCode {
-	}
+    record Arrow(String source) implements SourceCode {
+    }
 
-	/**
-	 * Supported syntax types for {@link SourceCode}.
-	 */
-	enum Syntax {
-		LAMBDA, ARROW
-	}
+    /**
+     * Supported syntax types for {@link SourceCode}.
+     */
+    enum Syntax {
+        LAMBDA, ARROW
+    }
 }
diff --git a/core/src/main/java/coffee/liz/lambda/ast/SourceComment.java b/core/src/main/java/coffee/liz/lambda/ast/SourceComment.java
index da6b5ab..8e50f5f 100644
--- a/core/src/main/java/coffee/liz/lambda/ast/SourceComment.java
+++ b/core/src/main/java/coffee/liz/lambda/ast/SourceComment.java
@@ -12,10 +12,10 @@ import lombok.NonNull;
  */
 public record SourceComment(@NonNull String text, @NonNull SourceSpan span) {
 
-	/**
-	 * Returns true if this comment is on the same line as the given span's end.
-	 */
-	public boolean isInlineAfter(final SourceSpan previous) {
-		return previous != null && previous.endLine() == this.span.startLine();
-	}
+    /**
+     * Returns true if this comment is on the same line as the given span's end.
+     */
+    public boolean isInlineAfter(final SourceSpan previous) {
+        return previous != null && previous.endLine() == this.span.startLine();
+    }
 }
diff --git a/core/src/main/java/coffee/liz/lambda/ast/SourceSpan.java b/core/src/main/java/coffee/liz/lambda/ast/SourceSpan.java
index 7df9bcd..80e06f9 100644
--- a/core/src/main/java/coffee/liz/lambda/ast/SourceSpan.java
+++ b/core/src/main/java/coffee/liz/lambda/ast/SourceSpan.java
@@ -13,12 +13,12 @@ package coffee.liz.lambda.ast;
  *            1-based column number where the span ends
  */
 public record SourceSpan(int startLine, int startColumn, int endLine, int endColumn) {
-	public static final SourceSpan UNKNOWN = new SourceSpan(0, 0, 0, 0);
+    public static final SourceSpan UNKNOWN = new SourceSpan(0, 0, 0, 0);
 
-	/**
-	 * Returns true if this span ends on the same line that the other span starts.
-	 */
-	public boolean isOnSameLine(final SourceSpan other) {
-		return this.endLine == other.startLine;
-	}
+    /**
+     * Returns true if this span ends on the same line that the other span starts.
+     */
+    public boolean isOnSameLine(final SourceSpan other) {
+        return this.endLine == other.startLine;
+    }
 }
diff --git a/core/src/main/java/coffee/liz/lambda/bind/ExternalBinding.java b/core/src/main/java/coffee/liz/lambda/bind/ExternalBinding.java
index 4895972..7a8ae40 100644
--- a/core/src/main/java/coffee/liz/lambda/bind/ExternalBinding.java
+++ b/core/src/main/java/coffee/liz/lambda/bind/ExternalBinding.java
@@ -14,10 +14,10 @@ import java.util.function.BiFunction;
  */
 public interface ExternalBinding extends BiFunction<Environment, Value, Value> {
 
-	/**
-	 * Returns the name used to reference this binding in environment.
-	 *
-	 * @return the binding name
-	 */
-	String getName();
+    /**
+     * Returns the name used to reference this binding in environment.
+     *
+     * @return the binding name
+     */
+    String getName();
 }
diff --git a/core/src/main/java/coffee/liz/lambda/bind/Tick.java b/core/src/main/java/coffee/liz/lambda/bind/Tick.java
index 0fa4de5..c4ad8ee 100644
--- a/core/src/main/java/coffee/liz/lambda/bind/Tick.java
+++ b/core/src/main/java/coffee/liz/lambda/bind/Tick.java
@@ -11,12 +11,12 @@ import java.util.concurrent.atomic.AtomicInteger;
  */
 @Getter
 public class Tick implements ExternalBinding {
-	private final String name = "Tick";
-	private final AtomicInteger counter = new AtomicInteger(0);
+    private final String name = "Tick";
+    private final AtomicInteger counter = new AtomicInteger(0);
 
-	@Override
-	public Value apply(final Environment environment, final Value value) {
-		counter.incrementAndGet();
-		return value;
-	}
+    @Override
+    public Value apply(final Environment environment, final Value value) {
+        counter.incrementAndGet();
+        return value;
+    }
 }
diff --git a/core/src/main/java/coffee/liz/lambda/bind/ToChurch.java b/core/src/main/java/coffee/liz/lambda/bind/ToChurch.java
index bfddd86..315622a 100644
--- a/core/src/main/java/coffee/liz/lambda/bind/ToChurch.java
+++ b/core/src/main/java/coffee/liz/lambda/bind/ToChurch.java
@@ -22,28 +22,28 @@ import lombok.Getter;
  */
 @Getter
 public class ToChurch implements ExternalBinding {
-	private final String name = "ToChurch";
+    private final String name = "ToChurch";
 
-	/**
-	 * Converts a free variable containing an integer string to a Church numeral.
-	 *
-	 * @param env
-	 *            the current environment
-	 * @param val
-	 *            a Free value whose name is an integer string
-	 * @return a Closure representing the Church numeral
-	 */
-	@Override
-	public Value apply(final Environment env, final Value val) {
-		final Free free = (Free) val;
-		final int n = Integer.parseInt(free.name());
+    /**
+     * Converts a free variable containing an integer string to a Church numeral.
+     *
+     * @param env
+     *            the current environment
+     * @param val
+     *            a Free value whose name is an integer string
+     * @return a Closure representing the Church numeral
+     */
+    @Override
+    public Value apply(final Environment env, final Value val) {
+        final Free free = (Free) val;
+        final int n = Integer.parseInt(free.name());
 
-		Expression body = new IdentifierExpression(Optional.empty(), SourceSpan.UNKNOWN, "x");
-		for (int i = 0; i < n; i++) {
-			body = new ApplicationExpression(Optional.empty(), SourceSpan.UNKNOWN,
-					new IdentifierExpression(Optional.empty(), SourceSpan.UNKNOWN, "f"), body);
-		}
+        Expression body = new IdentifierExpression(Optional.empty(), SourceSpan.UNKNOWN, "x");
+        for (int i = 0; i < n; i++) {
+            body = new ApplicationExpression(Optional.empty(), SourceSpan.UNKNOWN,
+                    new IdentifierExpression(Optional.empty(), SourceSpan.UNKNOWN, "f"), body);
+        }
 
-		return new Closure(env, "f", new AbstractionExpression(Optional.empty(), SourceSpan.UNKNOWN, "x", body));
-	}
+        return new Closure(env, "f", new AbstractionExpression(Optional.empty(), SourceSpan.UNKNOWN, "x", body));
+    }
 }
diff --git a/core/src/main/java/coffee/liz/lambda/eval/Environment.java b/core/src/main/java/coffee/liz/lambda/eval/Environment.java
index 8854719..a4ec24a 100644
--- a/core/src/main/java/coffee/liz/lambda/eval/Environment.java
+++ b/core/src/main/java/coffee/liz/lambda/eval/Environment.java
@@ -18,92 +18,92 @@ import java.util.stream.Collectors;
  */
 @RequiredArgsConstructor
 public final class Environment {
-	/** Named expansions */
-	private final Map<String, Expression> macros;
+    /** Named expansions */
+    private final Map<String, Expression> macros;
 
-	/** "FFI" */
-	private final Map<String, ExternalBinding> externalBindings;
+    /** "FFI" */
+    private final Map<String, ExternalBinding> externalBindings;
 
-	/** Variable name bound at this scope level. Null for root. */
-	@Nullable
-	private final String boundName;
+    /** Variable name bound at this scope level. Null for root. */
+    @Nullable
+    private final String boundName;
 
-	/** Lazily-evaluated value for boundName, or null for root. */
-	@Nullable
-	private final Supplier<Value> boundValue;
+    /** Lazily-evaluated value for boundName, or null for root. */
+    @Nullable
+    private final Supplier<Value> boundValue;
 
-	/** Enclosing scope, or null for root. Forms a linked list of bindings. */
-	@Nullable
-	private final Environment parent;
+    /** Enclosing scope, or null for root. Forms a linked list of bindings. */
+    @Nullable
+    private final Environment parent;
 
-	/**
-	 * Creates an environment from macro and external binding lists.
-	 *
-	 * @param macros
-	 *            program macro definitions
-	 * @param externalBindings
-	 *            external Java bindings for FFI
-	 * @return the new environment
-	 */
-	public static Environment from(final List<Macro> macros, final List<ExternalBinding> externalBindings) {
-		return new Environment(macros.stream().collect(Collectors.toMap(Macro::name, Macro::expression)),
-				externalBindings.stream().collect(Collectors.toMap(ExternalBinding::getName, Function.identity())),
-				null, null, null);
-	}
+    /**
+     * Creates an environment from macro and external binding lists.
+     *
+     * @param macros
+     *            program macro definitions
+     * @param externalBindings
+     *            external Java bindings for FFI
+     * @return the new environment
+     */
+    public static Environment from(final List<Macro> macros, final List<ExternalBinding> externalBindings) {
+        return new Environment(macros.stream().collect(Collectors.toMap(Macro::name, Macro::expression)),
+                externalBindings.stream().collect(Collectors.toMap(ExternalBinding::getName, Function.identity())),
+                null, null, null);
+    }
 
-	/**
-	 * Creates a child scope.
-	 *
-	 * @param name
-	 *            the variable name
-	 * @param value
-	 *            the value supplier (thunk)
-	 * @return a new environment with the binding added
-	 */
-	public Environment extend(final String name, final Supplier<Value> value) {
-		return new Environment(macros, externalBindings, name, value, this);
-	}
+    /**
+     * Creates a child scope.
+     *
+     * @param name
+     *            the variable name
+     * @param value
+     *            the value supplier (thunk)
+     * @return a new environment with the binding added
+     */
+    public Environment extend(final String name, final Supplier<Value> value) {
+        return new Environment(macros, externalBindings, name, value, this);
+    }
 
-	/**
-	 * Looks up a name, checking bindings, then macros, then external bindings.
-	 *
-	 * @param name
-	 *            the name to look up
-	 * @return the lookup result, or empty if not found
-	 */
-	public Optional<LookupResult> lookup(final String name) {
-		for (Environment env = this; env != null; env = env.parent) {
-			if (!name.equals(env.boundName)) {
-				continue;
-			}
-			return Optional.of(new LookupResult.Binding(env.boundValue));
-		}
+    /**
+     * Looks up a name, checking bindings, then macros, then external bindings.
+     *
+     * @param name
+     *            the name to look up
+     * @return the lookup result, or empty if not found
+     */
+    public Optional<LookupResult> lookup(final String name) {
+        for (Environment env = this; env != null; env = env.parent) {
+            if (!name.equals(env.boundName)) {
+                continue;
+            }
+            return Optional.of(new LookupResult.Binding(env.boundValue));
+        }
 
-		final Expression macro = macros.get(name);
-		if (macro != null) {
-			return Optional.of(new LookupResult.Macro(macro));
-		}
+        final Expression macro = macros.get(name);
+        if (macro != null) {
+            return Optional.of(new LookupResult.Macro(macro));
+        }
 
-		final ExternalBinding external = externalBindings.get(name);
-		if (external != null) {
-			return Optional.of(new LookupResult.External(external));
-		}
+        final ExternalBinding external = externalBindings.get(name);
+        if (external != null) {
+            return Optional.of(new LookupResult.External(external));
+        }
 
-		return Optional.empty();
-	}
+        return Optional.empty();
+    }
 
-	/**
-	 * Result of looking up a name in the environment.
-	 */
-	public sealed interface LookupResult {
-		/** A local variable binding. */
-		record Binding(Supplier<Value> value) implements LookupResult {
-		}
-		/** A macro definition. */
-		record Macro(Expression expression) implements LookupResult {
-		}
-		/** An external Java binding. */
-		record External(ExternalBinding binding) implements LookupResult {
-		}
-	}
+    /**
+     * Result of looking up a name in the environment.
+     */
+    public sealed interface LookupResult {
+        /** A local variable binding. */
+        record Binding(Supplier<Value> value) implements LookupResult {
+        }
+        /** A macro definition. */
+        record Macro(Expression expression) implements LookupResult {
+        }
+        /** An external Java binding. */
+        record External(ExternalBinding binding) implements LookupResult {
+        }
+    }
 }
diff --git a/core/src/main/java/coffee/liz/lambda/eval/EvaluationDepthExceededException.java b/core/src/main/java/coffee/liz/lambda/eval/EvaluationDepthExceededException.java
index 7926004..8f2ad2e 100644
--- a/core/src/main/java/coffee/liz/lambda/eval/EvaluationDepthExceededException.java
+++ b/core/src/main/java/coffee/liz/lambda/eval/EvaluationDepthExceededException.java
@@ -7,10 +7,10 @@ import lombok.Getter;
  */
 @Getter
 public final class EvaluationDepthExceededException extends RuntimeException {
-	private final int maxDepth;
+    private final int maxDepth;
 
-	public EvaluationDepthExceededException(final int maxDepth) {
-		super("Evaluation exceeded maximum depth of " + maxDepth);
-		this.maxDepth = maxDepth;
-	}
+    public EvaluationDepthExceededException(final int maxDepth) {
+        super("Evaluation exceeded maximum depth of " + maxDepth);
+        this.maxDepth = maxDepth;
+    }
 }
diff --git a/core/src/main/java/coffee/liz/lambda/eval/NormalOrderEvaluator.java b/core/src/main/java/coffee/liz/lambda/eval/NormalOrderEvaluator.java
index 28eb69b..d9bcba3 100644
--- a/core/src/main/java/coffee/liz/lambda/eval/NormalOrderEvaluator.java
+++ b/core/src/main/java/coffee/liz/lambda/eval/NormalOrderEvaluator.java
@@ -18,84 +18,84 @@ import coffee.liz.lambda.eval.Value.Free;
  */
 public final class NormalOrderEvaluator {
 
-	public static final int DEFAULT_MAX_DEPTH = 140;
+    public static final int DEFAULT_MAX_DEPTH = 140;
 
-	/**
-	 * Evaluates an expression in the given environment with default depth limit.
-	 *
-	 * @param term
-	 *            the expression to evaluate
-	 * @param env
-	 *            the environment containing bindings
-	 * @return the resulting value
-	 * @throws EvaluationDepthExceededException
-	 *             if evaluation exceeds {@link #DEFAULT_MAX_DEPTH}
-	 */
-	public static Value evaluate(final Expression term, final Environment env) {
-		return evaluate(term, env, DEFAULT_MAX_DEPTH);
-	}
+    /**
+     * Evaluates an expression in the given environment with default depth limit.
+     *
+     * @param term
+     *            the expression to evaluate
+     * @param env
+     *            the environment containing bindings
+     * @return the resulting value
+     * @throws EvaluationDepthExceededException
+     *             if evaluation exceeds {@link #DEFAULT_MAX_DEPTH}
+     */
+    public static Value evaluate(final Expression term, final Environment env) {
+        return evaluate(term, env, DEFAULT_MAX_DEPTH);
+    }
 
-	/**
-	 * Evaluates an expression in the given environment with specified depth limit.
-	 *
-	 * @param term
-	 *            the expression to evaluate
-	 * @param env
-	 *            the environment containing bindings
-	 * @param maxDepth
-	 *            maximum evaluation depth
-	 * @return the resulting value
-	 * @throws EvaluationDepthExceededException
-	 *             if evaluation exceeds maxDepth
-	 */
-	public static Value evaluate(final Expression term, final Environment env, final int maxDepth) {
-		return evaluate(term, env, maxDepth, 0);
-	}
+    /**
+     * Evaluates an expression in the given environment with specified depth limit.
+     *
+     * @param term
+     *            the expression to evaluate
+     * @param env
+     *            the environment containing bindings
+     * @param maxDepth
+     *            maximum evaluation depth
+     * @return the resulting value
+     * @throws EvaluationDepthExceededException
+     *             if evaluation exceeds maxDepth
+     */
+    public static Value evaluate(final Expression term, final Environment env, final int maxDepth) {
+        return evaluate(term, env, maxDepth, 0);
+    }
 
-	private static Value evaluate(final Expression term, final Environment env, final int maxDepth, final int depth) {
-		if (depth > maxDepth) {
-			throw new EvaluationDepthExceededException(maxDepth);
-		}
+    private static Value evaluate(final Expression term, final Environment env, final int maxDepth, final int depth) {
+        if (depth > maxDepth) {
+            throw new EvaluationDepthExceededException(maxDepth);
+        }
 
-		return switch (term) {
-			case IdentifierExpression(var _, var _, final String name) ->
-				env.lookup(name).map(result -> switch (result) {
-					case LookupResult.Binding(final var value) -> value.get();
-					case LookupResult.Macro(final var expr) -> evaluate(expr, env, maxDepth, depth + 1);
-					case LookupResult.External(final var binding) -> new Free(binding.getName());
-				}).orElseGet(() -> new Free(name));
+        return switch (term) {
+            case IdentifierExpression(var _, var _, final String name) ->
+                env.lookup(name).map(result -> switch (result) {
+                    case LookupResult.Binding(final var value) -> value.get();
+                    case LookupResult.Macro(final var expr) -> evaluate(expr, env, maxDepth, depth + 1);
+                    case LookupResult.External(final var binding) -> new Free(binding.getName());
+                }).orElseGet(() -> new Free(name));
 
-			case AbstractionExpression(var _, var _, final String parameter, final Expression body) ->
-				new Closure(env, parameter, body);
+            case AbstractionExpression(var _, var _, final String parameter, final Expression body) ->
+                new Closure(env, parameter, body);
 
-			case ApplicationExpression(var _, var _, final Expression func, final Expression arg) ->
-				apply(evaluate(func, env, maxDepth, depth + 1), arg, env, maxDepth, depth + 1);
-		};
-	}
+            case ApplicationExpression(var _, var _, final Expression func, final Expression arg) ->
+                apply(evaluate(func, env, maxDepth, depth + 1), arg, env, maxDepth, depth + 1);
+        };
+    }
 
-	private static Value apply(final Value funcVal, final Expression arg, final Environment argEnv, final int maxDepth,
-			final int depth) {
-		if (depth > maxDepth) {
-			throw new EvaluationDepthExceededException(maxDepth);
-		}
+    private static Value apply(final Value funcVal, final Expression arg, final Environment argEnv, final int maxDepth,
+            final int depth) {
+        if (depth > maxDepth) {
+            throw new EvaluationDepthExceededException(maxDepth);
+        }
 
-		return switch (funcVal) {
-			case Closure(final Environment closureEnv, final String parameter, final Expression body) -> {
-				final Thunk<Value> thunk = new Thunk<>(() -> evaluate(arg, argEnv, maxDepth, depth + 1));
-				final Environment newEnv = closureEnv.extend(parameter, thunk);
-				yield evaluate(body, newEnv, maxDepth, depth + 1);
-			}
+        return switch (funcVal) {
+            case Closure(final Environment closureEnv, final String parameter, final Expression body) -> {
+                final Thunk<Value> thunk = new Thunk<>(() -> evaluate(arg, argEnv, maxDepth, depth + 1));
+                final Environment newEnv = closureEnv.extend(parameter, thunk);
+                yield evaluate(body, newEnv, maxDepth, depth + 1);
+            }
 
-			case Free(final String name) ->
-				argEnv.lookup(name).filter(r -> r instanceof LookupResult.External).map(r -> {
-					final ExternalBinding binding = ((LookupResult.External) r).binding();
-					return binding.apply(argEnv, evaluate(arg, argEnv, maxDepth, depth + 1));
-				}).orElseGet(() -> new Application(funcVal, evaluate(arg, argEnv, maxDepth, depth + 1)));
+            case Free(final String name) ->
+                argEnv.lookup(name).filter(r -> r instanceof LookupResult.External).map(r -> {
+                    final ExternalBinding binding = ((LookupResult.External) r).binding();
+                    return binding.apply(argEnv, evaluate(arg, argEnv, maxDepth, depth + 1));
+                }).orElseGet(() -> new Application(funcVal, evaluate(arg, argEnv, maxDepth, depth + 1)));
 
-			case Application app -> {
-				final Value argVal = evaluate(arg, argEnv, maxDepth, depth + 1);
-				yield new Application(app, argVal);
-			}
-		};
-	}
+            case Application app -> {
+                final Value argVal = evaluate(arg, argEnv, maxDepth, depth + 1);
+                yield new Application(app, argVal);
+            }
+        };
+    }
 }
diff --git a/core/src/main/java/coffee/liz/lambda/eval/Thunk.java b/core/src/main/java/coffee/liz/lambda/eval/Thunk.java
index 07c89bf..fdbda93 100644
--- a/core/src/main/java/coffee/liz/lambda/eval/Thunk.java
+++ b/core/src/main/java/coffee/liz/lambda/eval/Thunk.java
@@ -12,16 +12,16 @@ import java.util.function.Supplier;
  */
 @RequiredArgsConstructor
 public final class Thunk<T> implements Supplier<T> {
-	private final Supplier<T> thinker; // https://www.youtube.com/shorts/Dzksib8YxSY
-	private T cached = null;
-	private boolean evaluated = false;
+    private final Supplier<T> thinker; // https://www.youtube.com/shorts/Dzksib8YxSY
+    private T cached = null;
+    private boolean evaluated = false;
 
-	@Override
-	public T get() {
-		if (!evaluated) {
-			cached = thinker.get();
-			evaluated = true;
-		}
-		return cached;
-	}
+    @Override
+    public T get() {
+        if (!evaluated) {
+            cached = thinker.get();
+            evaluated = true;
+        }
+        return cached;
+    }
 }
\ No newline at end of file
diff --git a/core/src/main/java/coffee/liz/lambda/eval/Value.java b/core/src/main/java/coffee/liz/lambda/eval/Value.java
index 58b9ba4..dc459ff 100644
--- a/core/src/main/java/coffee/liz/lambda/eval/Value.java
+++ b/core/src/main/java/coffee/liz/lambda/eval/Value.java
@@ -7,36 +7,36 @@ import coffee.liz.lambda.ast.Expression;
  */
 public sealed interface Value permits Value.Closure, Value.Application, Value.Free {
 
-	/**
-	 * A closure capturing an environment, parameter, and body.
-	 *
-	 * @param env
-	 *            the captured environment
-	 * @param parameter
-	 *            the bound parameter name
-	 * @param body
-	 *            the lambda body expression
-	 */
-	record Closure(Environment env, String parameter, Expression body) implements Value {
-	}
+    /**
+     * A closure capturing an environment, parameter, and body.
+     *
+     * @param env
+     *            the captured environment
+     * @param parameter
+     *            the bound parameter name
+     * @param body
+     *            the lambda body expression
+     */
+    record Closure(Environment env, String parameter, Expression body) implements Value {
+    }
 
-	/**
-	 * A symbolic application of a function to an argument.
-	 *
-	 * @param function
-	 *            the function
-	 * @param argument
-	 *            the argument
-	 */
-	record Application(Value function, Value argument) implements Value {
-	}
+    /**
+     * A symbolic application of a function to an argument.
+     *
+     * @param function
+     *            the function
+     * @param argument
+     *            the argument
+     */
+    record Application(Value function, Value argument) implements Value {
+    }
 
-	/**
-	 * A free variable.
-	 *
-	 * @param name
-	 *            the variable name
-	 */
-	record Free(String name) implements Value {
-	}
+    /**
+     * A free variable.
+     *
+     * @param name
+     *            the variable name
+     */
+    record Free(String name) implements Value {
+    }
 }
diff --git a/core/src/main/java/coffee/liz/lambda/format/Formatter.java b/core/src/main/java/coffee/liz/lambda/format/Formatter.java
index 1ac3e95..e4fbc0c 100644
--- a/core/src/main/java/coffee/liz/lambda/format/Formatter.java
+++ b/core/src/main/java/coffee/liz/lambda/format/Formatter.java
@@ -21,218 +21,218 @@ import java.util.Optional;
 @RequiredArgsConstructor
 public final class Formatter {
 
-	private final Syntax syntax;
+    private final Syntax syntax;
 
-	public String format(final LambdaProgram program) {
-		final StringBuilder sb = new StringBuilder();
-		SourceSpan previousEnd = null;
+    public String format(final LambdaProgram program) {
+        final StringBuilder sb = new StringBuilder();
+        SourceSpan previousEnd = null;
 
-		for (int i = 0; i < program.macros().size(); i++) {
-			final Macro macro = program.macros().get(i);
+        for (int i = 0; i < program.macros().size(); i++) {
+            final Macro macro = program.macros().get(i);
 
-			if (macro.comment().isPresent()) {
-				final SourceComment comment = macro.comment().get();
-				final String leadingPart = getLeadingCommentPart(comment, previousEnd);
-				if (!leadingPart.isEmpty()) {
-					sb.append(leadingPart);
-					if (!leadingPart.endsWith("\n")) {
-						sb.append("\n");
-					}
-				}
-			}
+            if (macro.comment().isPresent()) {
+                final SourceComment comment = macro.comment().get();
+                final String leadingPart = getLeadingCommentPart(comment, previousEnd);
+                if (!leadingPart.isEmpty()) {
+                    sb.append(leadingPart);
+                    if (!leadingPart.endsWith("\n")) {
+                        sb.append("\n");
+                    }
+                }
+            }
 
-			sb.append("let ").append(macro.name()).append(" = ");
-			sb.append(formatExpression(macro.expression(), false));
-			sb.append(";");
+            sb.append("let ").append(macro.name()).append(" = ");
+            sb.append(formatExpression(macro.expression(), false));
+            sb.append(";");
 
-			final Optional<String> inlineComment = getInlineCommentAfter(macro.span(), program, i);
-			inlineComment.ifPresent(c -> sb.append(" ").append(c));
-			sb.append("\n");
+            final Optional<String> inlineComment = getInlineCommentAfter(macro.span(), program, i);
+            inlineComment.ifPresent(c -> sb.append(" ").append(c));
+            sb.append("\n");
 
-			previousEnd = macro.span();
-		}
+            previousEnd = macro.span();
+        }
 
-		boolean isTrailingComment = false;
-		boolean inlinePartAlreadyOutput = false;
+        boolean isTrailingComment = false;
+        boolean inlinePartAlreadyOutput = false;
 
-		if (program.expression().comment().isPresent()) {
-			final SourceComment comment = program.expression().comment().get();
+        if (program.expression().comment().isPresent()) {
+            final SourceComment comment = program.expression().comment().get();
 
-			isTrailingComment = comment.span().startLine() >= program.expression().span().startLine()
-					&& comment.span().startColumn() > program.expression().span().startColumn();
+            isTrailingComment = comment.span().startLine() >= program.expression().span().startLine()
+                    && comment.span().startColumn() > program.expression().span().startColumn();
 
-			if (!isTrailingComment) {
-				inlinePartAlreadyOutput = previousEnd != null && comment.isInlineAfter(previousEnd);
+            if (!isTrailingComment) {
+                inlinePartAlreadyOutput = previousEnd != null && comment.isInlineAfter(previousEnd);
 
-				final String leadingPart = getLeadingCommentPart(comment, previousEnd);
-				if (!leadingPart.isEmpty()) {
-					sb.append(leadingPart);
-					if (!leadingPart.endsWith("\n")) {
-						sb.append("\n");
-					}
-				} else if (!program.macros().isEmpty()) {
-					sb.append("\n");
-				}
-			} else if (!program.macros().isEmpty()) {
-				sb.append("\n");
-			}
-		} else if (!program.macros().isEmpty()) {
-			sb.append("\n");
-		}
+                final String leadingPart = getLeadingCommentPart(comment, previousEnd);
+                if (!leadingPart.isEmpty()) {
+                    sb.append(leadingPart);
+                    if (!leadingPart.endsWith("\n")) {
+                        sb.append("\n");
+                    }
+                } else if (!program.macros().isEmpty()) {
+                    sb.append("\n");
+                }
+            } else if (!program.macros().isEmpty()) {
+                sb.append("\n");
+            }
+        } else if (!program.macros().isEmpty()) {
+            sb.append("\n");
+        }
 
-		sb.append(formatExpression(program.expression(), false));
+        sb.append(formatExpression(program.expression(), false));
 
-		if (program.expression().comment().isPresent() && !inlinePartAlreadyOutput && isTrailingComment) {
-			sb.append(" ").append(program.expression().comment().get().text());
-		}
+        if (program.expression().comment().isPresent() && !inlinePartAlreadyOutput && isTrailingComment) {
+            sb.append(" ").append(program.expression().comment().get().text());
+        }
 
-		return sb.toString();
-	}
+        return sb.toString();
+    }
 
-	/**
-	 * Gets the inline portion of a comment (first line if on same line as previous
-	 * element).
-	 */
-	private String getInlineCommentPart(final SourceComment comment, final SourceSpan previousEnd) {
-		if (previousEnd == null || !comment.isInlineAfter(previousEnd)) {
-			return "";
-		}
-		final String text = comment.text();
-		final int newlineIndex = text.indexOf('\n');
-		return newlineIndex == -1 ? text : text.substring(0, newlineIndex);
-	}
+    /**
+     * Gets the inline portion of a comment (first line if on same line as previous
+     * element).
+     */
+    private String getInlineCommentPart(final SourceComment comment, final SourceSpan previousEnd) {
+        if (previousEnd == null || !comment.isInlineAfter(previousEnd)) {
+            return "";
+        }
+        final String text = comment.text();
+        final int newlineIndex = text.indexOf('\n');
+        return newlineIndex == -1 ? text : text.substring(0, newlineIndex);
+    }
 
-	/**
-	 * Gets the leading portion of a comment (all lines except inline first line).
-	 */
-	private String getLeadingCommentPart(final SourceComment comment, final SourceSpan previousEnd) {
-		if (previousEnd == null || !comment.isInlineAfter(previousEnd)) {
-			return comment.text();
-		}
-		final String text = comment.text();
-		final int newlineIndex = text.indexOf('\n');
-		return newlineIndex == -1 ? "" : text.substring(newlineIndex + 1);
-	}
+    /**
+     * Gets the leading portion of a comment (all lines except inline first line).
+     */
+    private String getLeadingCommentPart(final SourceComment comment, final SourceSpan previousEnd) {
+        if (previousEnd == null || !comment.isInlineAfter(previousEnd)) {
+            return comment.text();
+        }
+        final String text = comment.text();
+        final int newlineIndex = text.indexOf('\n');
+        return newlineIndex == -1 ? "" : text.substring(newlineIndex + 1);
+    }
 
-	/**
-	 * Gets the inline comment that appears after the given span, if any.
-	 */
-	private Optional<String> getInlineCommentAfter(final SourceSpan span, final LambdaProgram program,
-			final int macroIndex) {
-		if (macroIndex + 1 < program.macros().size()) {
-			final Macro nextMacro = program.macros().get(macroIndex + 1);
-			if (nextMacro.comment().isPresent() && nextMacro.comment().get().isInlineAfter(span)) {
-				final String inlinePart = getInlineCommentPart(nextMacro.comment().get(), span);
-				if (!inlinePart.isEmpty()) {
-					return Optional.of(inlinePart);
-				}
-			}
-		}
-		if (macroIndex == program.macros().size() - 1 && program.expression().comment().isPresent()
-				&& program.expression().comment().get().isInlineAfter(span)) {
-			final String inlinePart = getInlineCommentPart(program.expression().comment().get(), span);
-			if (!inlinePart.isEmpty()) {
-				return Optional.of(inlinePart);
-			}
-		}
-		return Optional.empty();
-	}
+    /**
+     * Gets the inline comment that appears after the given span, if any.
+     */
+    private Optional<String> getInlineCommentAfter(final SourceSpan span, final LambdaProgram program,
+            final int macroIndex) {
+        if (macroIndex + 1 < program.macros().size()) {
+            final Macro nextMacro = program.macros().get(macroIndex + 1);
+            if (nextMacro.comment().isPresent() && nextMacro.comment().get().isInlineAfter(span)) {
+                final String inlinePart = getInlineCommentPart(nextMacro.comment().get(), span);
+                if (!inlinePart.isEmpty()) {
+                    return Optional.of(inlinePart);
+                }
+            }
+        }
+        if (macroIndex == program.macros().size() - 1 && program.expression().comment().isPresent()
+                && program.expression().comment().get().isInlineAfter(span)) {
+            final String inlinePart = getInlineCommentPart(program.expression().comment().get(), span);
+            if (!inlinePart.isEmpty()) {
+                return Optional.of(inlinePart);
+            }
+        }
+        return Optional.empty();
+    }
 
-	private String formatExpression(final Expression expr, final boolean needsParens) {
-		return switch (expr) {
-			case AbstractionExpression abs -> formatAbstraction(abs, needsParens);
-			case ApplicationExpression app -> formatApplication(app, needsParens);
-			case IdentifierExpression id -> id.name();
-		};
-	}
+    private String formatExpression(final Expression expr, final boolean needsParens) {
+        return switch (expr) {
+            case AbstractionExpression abs -> formatAbstraction(abs, needsParens);
+            case ApplicationExpression app -> formatApplication(app, needsParens);
+            case IdentifierExpression id -> id.name();
+        };
+    }
 
-	private String formatAbstraction(final AbstractionExpression abs, final boolean needsParens) {
-		final StringBuilder sb = new StringBuilder();
+    private String formatAbstraction(final AbstractionExpression abs, final boolean needsParens) {
+        final StringBuilder sb = new StringBuilder();
 
-		if (needsParens) {
-			sb.append("(");
-		}
-		switch (syntax) {
-			case LAMBDA -> {
-				sb.append("λ").append(abs.parameter()).append(".");
-				sb.append(formatExpression(abs.body(), false));
-			}
-			case ARROW -> {
-				sb.append(abs.parameter()).append(" -> ");
-				sb.append(formatExpression(abs.body(), false));
-			}
-		}
-		if (needsParens) {
-			sb.append(")");
-		}
+        if (needsParens) {
+            sb.append("(");
+        }
+        switch (syntax) {
+            case LAMBDA -> {
+                sb.append("λ").append(abs.parameter()).append(".");
+                sb.append(formatExpression(abs.body(), false));
+            }
+            case ARROW -> {
+                sb.append(abs.parameter()).append(" -> ");
+                sb.append(formatExpression(abs.body(), false));
+            }
+        }
+        if (needsParens) {
+            sb.append(")");
+        }
 
-		return sb.toString();
-	}
+        return sb.toString();
+    }
 
-	private String formatApplication(final ApplicationExpression app, final boolean needsParens) {
-		return switch (syntax) {
-			case LAMBDA -> formatLambdaApplication(app, needsParens);
-			case ARROW -> formatArrowApplication(app);
-		};
-	}
+    private String formatApplication(final ApplicationExpression app, final boolean needsParens) {
+        return switch (syntax) {
+            case LAMBDA -> formatLambdaApplication(app, needsParens);
+            case ARROW -> formatArrowApplication(app);
+        };
+    }
 
-	private String formatLambdaApplication(final ApplicationExpression app, final boolean needsParens) {
-		final StringBuilder sb = new StringBuilder();
+    private String formatLambdaApplication(final ApplicationExpression app, final boolean needsParens) {
+        final StringBuilder sb = new StringBuilder();
 
-		if (needsParens) {
-			sb.append("(");
-		}
+        if (needsParens) {
+            sb.append("(");
+        }
 
-		final boolean funcNeedsParens = app.applicable() instanceof AbstractionExpression;
-		sb.append(formatExpression(app.applicable(), funcNeedsParens));
+        final boolean funcNeedsParens = app.applicable() instanceof AbstractionExpression;
+        sb.append(formatExpression(app.applicable(), funcNeedsParens));
 
-		sb.append(" ");
+        sb.append(" ");
 
-		final boolean argNeedsParens = app.argument() instanceof ApplicationExpression
-				|| app.argument() instanceof AbstractionExpression;
-		sb.append(formatExpression(app.argument(), argNeedsParens));
+        final boolean argNeedsParens = app.argument() instanceof ApplicationExpression
+                || app.argument() instanceof AbstractionExpression;
+        sb.append(formatExpression(app.argument(), argNeedsParens));
 
-		if (needsParens) {
-			sb.append(")");
-		}
+        if (needsParens) {
+            sb.append(")");
+        }
 
-		return sb.toString();
-	}
+        return sb.toString();
+    }
 
-	private String formatArrowApplication(final ApplicationExpression app) {
-		final StringBuilder sb = new StringBuilder();
+    private String formatArrowApplication(final ApplicationExpression app) {
+        final StringBuilder sb = new StringBuilder();
 
-		Expression func = app.applicable();
-		final List<Expression> args = new ArrayList<>();
-		args.add(app.argument());
+        Expression func = app.applicable();
+        final List<Expression> args = new ArrayList<>();
+        args.add(app.argument());
 
-		while (func instanceof ApplicationExpression appFunc) {
-			args.addFirst(appFunc.argument());
-			func = appFunc.applicable();
-		}
+        while (func instanceof ApplicationExpression appFunc) {
+            args.addFirst(appFunc.argument());
+            func = appFunc.applicable();
+        }
 
-		final boolean funcNeedsParens = func instanceof AbstractionExpression;
-		if (funcNeedsParens) {
-			sb.append("(");
-		}
-		sb.append(formatExpression(func, false));
-		if (funcNeedsParens) {
-			sb.append(")");
-		}
+        final boolean funcNeedsParens = func instanceof AbstractionExpression;
+        if (funcNeedsParens) {
+            sb.append("(");
+        }
+        sb.append(formatExpression(func, false));
+        if (funcNeedsParens) {
+            sb.append(")");
+        }
 
-		for (final Expression arg : args) {
-			sb.append("(");
-			sb.append(formatExpression(arg, false));
-			sb.append(")");
-		}
+        for (final Expression arg : args) {
+            sb.append("(");
+            sb.append(formatExpression(arg, false));
+            sb.append(")");
+        }
 
-		return sb.toString();
-	}
+        return sb.toString();
+    }
 
-	/**
-	 * Formats a program in the specified syntax.
-	 */
-	public static String emit(final LambdaProgram program, final Syntax syntax) {
-		return new Formatter(syntax).format(program);
-	}
+    /**
+     * Formats a program in the specified syntax.
+     */
+    public static String emit(final LambdaProgram program, final Syntax syntax) {
+        return new Formatter(syntax).format(program);
+    }
 }