Declare sum types

6 files changed, 66 insertions, 2 deletions

diff --git a/src/main/java/org/shedlang/compiler/ast/typed/TypedNamespaceStatementNode.java b/src/main/java/org/shedlang/compiler/ast/typed/TypedNamespaceStatementNode.java
index 9a5e766a..654e073d 100644
--- a/src/main/java/org/shedlang/compiler/ast/typed/TypedNamespaceStatementNode.java
+++ b/src/main/java/org/shedlang/compiler/ast/typed/TypedNamespaceStatementNode.java
@@ -1,4 +1,4 @@
 package org.shedlang.compiler.ast.typed;
 
-public sealed interface TypedNamespaceStatementNode extends TypedNode permits TypedAssignNode, TypedFunctionDefinitionNode, TypedStructDefinitionNode {
+public sealed interface TypedNamespaceStatementNode extends TypedNode permits TypedAssignNode, TypedFunctionDefinitionNode, TypedStructDefinitionNode, TypedSumTypeDefinitionNode {
 }
diff --git a/src/main/java/org/shedlang/compiler/ast/typed/TypedSumTypeDefinitionNode.java b/src/main/java/org/shedlang/compiler/ast/typed/TypedSumTypeDefinitionNode.java
new file mode 100644
index 00000000..851e64e8
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/ast/typed/TypedSumTypeDefinitionNode.java
@@ -0,0 +1,9 @@
+package org.shedlang.compiler.ast.typed;
+
+import org.shedlang.compiler.sources.Source;
+
+public record TypedSumTypeDefinitionNode(
+    String name,
+    Source source
+) implements TypedNamespaceStatementNode {
+}
diff --git a/src/main/java/org/shedlang/compiler/ast/untyped/UntypedSumTypeDefinitionNode.java b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedSumTypeDefinitionNode.java
index 681c4506..84f46711 100644
--- a/src/main/java/org/shedlang/compiler/ast/untyped/UntypedSumTypeDefinitionNode.java
+++ b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedSumTypeDefinitionNode.java
@@ -1,6 +1,7 @@
 package org.shedlang.compiler.ast.untyped;
 
 import org.shedlang.compiler.sources.Source;
+import org.shedlang.compiler.sources.Sources;
 
 import java.util.List;
 
@@ -9,4 +10,21 @@ public record UntypedSumTypeDefinitionNode(
     List<UntypedTypeLevelExpressionNode> variants,
     Source source
 ) implements UntypedNamespaceStatementNode {
+    public static Builder builder() {
+        return new Builder("DefaultSumTypeName");
+    }
+
+    public record Builder(String name) {
+        public UntypedSumTypeDefinitionNode build() {
+            return new UntypedSumTypeDefinitionNode(
+                name,
+                List.of(),
+                Sources.NULL
+            );
+        }
+
+        public Builder withName(String name) {
+            return new Builder(name);
+        }
+    }
 }
diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
index c630b9dc..539b9a9d 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -799,7 +799,7 @@ public class TypeChecker {
                 typeCheckStepsStructDefinition(structDefinition);
 
             case UntypedSumTypeDefinitionNode sumTypeDefinition ->
-                throw new UnsupportedOperationException("TODO");
+                typeCheckStepsSumTypeDefinition(sumTypeDefinition);
         };
     }
 
@@ -907,6 +907,29 @@ public class TypeChecker {
         };
     }
 
+    private static TypeCheckSteps<? extends TypedNamespaceStatementNode> typeCheckStepsSumTypeDefinition(
+        UntypedSumTypeDefinitionNode untyped
+    ) {
+        return new TypeCheckSteps<TypedNamespaceStatementNode>() {
+            @Override
+            public TypeCheckerContext declareTypes(TypeCheckerContext context) {
+                var namespaceName = context.namespaceName()
+                    .orElseThrow(() -> new CannotDefineSumTypeOutsideOfNamespace(untyped.source()));
+
+                var type = new SumType(namespaceName, untyped.name());
+
+                context = context.addLexicalState(untyped.name(), type);
+
+                return context.define(untyped.name(), Types.metaType(type), untyped.source());
+            }
+
+            @Override
+            public TypeCheckerResult<TypedNamespaceStatementNode> finish(TypeCheckerContext context) {
+                return context.toResult(null);
+            }
+        };
+    }
+
     @SuppressWarnings("unchecked")
     static <T extends TypeLevelValue> TypedTypeLevelExpressionNode<T> typeCheckTypeLevelExpression(
         TypeSetTypeLevelValue<T> valueType,
diff --git a/src/main/java/org/shedlang/compiler/typechecker/errors/CannotDefineSumTypeOutsideOfNamespace.java b/src/main/java/org/shedlang/compiler/typechecker/errors/CannotDefineSumTypeOutsideOfNamespace.java
new file mode 100644
index 00000000..d3f9c48c
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/typechecker/errors/CannotDefineSumTypeOutsideOfNamespace.java
@@ -0,0 +1,10 @@
+package org.shedlang.compiler.typechecker.errors;
+
+import org.shedlang.compiler.errors.InternalCompilerError;
+import org.shedlang.compiler.sources.Source;
+
+public class CannotDefineSumTypeOutsideOfNamespace extends InternalCompilerError {
+    public CannotDefineSumTypeOutsideOfNamespace(Source source) {
+        super("Cannot define sum type outside of namespace", source);
+    }
+}
diff --git a/src/main/java/org/shedlang/compiler/types/Types.java b/src/main/java/org/shedlang/compiler/types/Types.java
index 5600d1d9..3e5e1b39 100644
--- a/src/main/java/org/shedlang/compiler/types/Types.java
+++ b/src/main/java/org/shedlang/compiler/types/Types.java
@@ -18,6 +18,10 @@ public class Types {
         return new StructType(namespaceName, name);
     }
 
+    public static SumType sum(NamespaceName namespaceName, String name) {
+        return new SumType(namespaceName, name);
+    }
+
     public static TupleType tuple(List<Type> elements) {
         return new TupleType(elements);
     }