From 6d18d2156ae4063eee04ca467727e0ec0c4404cc Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sat, 30 Sep 2023 11:22:24 +0100
Subject: Add SumType

---
 src/main/java/org/shedlang/compiler/types/SumType.java | 11 +++++++++++
 src/main/java/org/shedlang/compiler/types/Type.java    |  2 +-
 2 files changed, 12 insertions(+), 1 deletion(-)
 create mode 100644 src/main/java/org/shedlang/compiler/types/SumType.java

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/types/SumType.java b/src/main/java/org/shedlang/compiler/types/SumType.java
new file mode 100644
index 00000000..8c293fca
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/types/SumType.java
@@ -0,0 +1,11 @@
+package org.shedlang.compiler.types;
+
+/**
+ * A discriminated union of several different types.
+ */
+public record SumType(NamespaceName namespaceName, String name) implements Type {
+    @Override
+    public String describe() {
+        return namespaceName.toString() + "." + name;
+    }
+}
diff --git a/src/main/java/org/shedlang/compiler/types/Type.java b/src/main/java/org/shedlang/compiler/types/Type.java
index b88cf42b..a1de4068 100644
--- a/src/main/java/org/shedlang/compiler/types/Type.java
+++ b/src/main/java/org/shedlang/compiler/types/Type.java
@@ -6,5 +6,5 @@ package org.shedlang.compiler.types;
  * found through auxiliary data.
  */
 public sealed interface Type extends TypeLevelValue
-    permits BoolType, BottomType, FunctionType, IntType, NamespaceType, StringType, StructType, TopType, TupleType, TypeLevelValueType, UnitType {
+    permits BoolType, BottomType, FunctionType, IntType, NamespaceType, StringType, StructType, SumType, TopType, TupleType, TypeLevelValueType, UnitType {
 }
-- 
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