Require explicit exit behaviour of handler methods

2 files changed, 12 insertions, 0 deletions

diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
index 57798421..0bb29d5f 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -598,6 +598,8 @@ public class TypeChecker {
             case TypedFunctionStatementBehaviour.Continue continue_ -> {
                 if (context.returnTypeState() instanceof ReturnTypeState.ImplicitLowerBound implicitLowerBound) {
                     checkIsSubType(Types.UNIT, implicitLowerBound.type(), untyped.source(), context);
+                } else if (context.returnTypeState() instanceof ReturnTypeState.EffectHandler effectHandler) {
+                    throw new EffectHandlerMethodMustResumeOrExitError(untyped.source());
                 } else {
                     context = typeCheckFunctionReturnValue(Types.UNIT, untyped.source(), context);
                 }
diff --git a/src/main/java/org/shedlang/compiler/typechecker/errors/EffectHandlerMethodMustResumeOrExitError.java b/src/main/java/org/shedlang/compiler/typechecker/errors/EffectHandlerMethodMustResumeOrExitError.java
new file mode 100644
index 00000000..f46429d5
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/typechecker/errors/EffectHandlerMethodMustResumeOrExitError.java
@@ -0,0 +1,10 @@
+package org.shedlang.compiler.typechecker.errors;
+
+import org.shedlang.compiler.errors.SourceError;
+import org.shedlang.compiler.sources.Source;
+
+public class EffectHandlerMethodMustResumeOrExitError extends SourceError {
+    public EffectHandlerMethodMustResumeOrExitError(Source source) {
+        super("Effect handler methods must resume or exit", source);
+    }
+}