3 files changed, 10 insertions, 1 deletions
diff --git a/src/main/java/org/shedlang/compiler/types/Type.java b/src/main/java/org/shedlang/compiler/types/Type.java
index df8cebc5..b104f137 100644
--- a/src/main/java/org/shedlang/compiler/types/Type.java
+++ b/src/main/java/org/shedlang/compiler/types/Type.java
@@ -1,4 +1,4 @@
 package org.shedlang.compiler.types;
 
-public sealed interface Type permits StringType {
+public sealed interface Type permits StringType, UnitType {
 }
diff --git a/src/main/java/org/shedlang/compiler/types/Types.java b/src/main/java/org/shedlang/compiler/types/Types.java
index 7c3556a5..0151f7ad 100644
--- a/src/main/java/org/shedlang/compiler/types/Types.java
+++ b/src/main/java/org/shedlang/compiler/types/Types.java
@@ -5,4 +5,5 @@ public class Types {
     }
 
     public static final Type STRING = StringType.INSTANCE;
+    public static final Type UNIT = UnitType.INSTANCE;
 }
diff --git a/src/main/java/org/shedlang/compiler/types/UnitType.java b/src/main/java/org/shedlang/compiler/types/UnitType.java
new file mode 100644
index 00000000..a84b66bd
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/types/UnitType.java
@@ -0,0 +1,8 @@
+package org.shedlang.compiler.types;
+
+public final class UnitType implements Type {
+    private UnitType() {
+    }
+
+    static final UnitType INSTANCE = new UnitType();
+}