From 04511855a22f07d595789520aa8beabaa642a0e6 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sun, 12 Nov 2023 11:54:52 +0000
Subject: Narrow handled effect type in TypedTryNode

---
 .../shedlang/compiler/ast/typed/TypedTryNode.java    |  4 ++--
 .../shedlang/compiler/typechecker/TypeChecker.java   | 17 +++++++++--------
 .../errors/NotUserDefinedEffectError.java            | 18 ------------------
 .../typechecker/typesets/TypeSetTypeLevelValue.java  |  2 +-
 .../typesets/TypeSetUserDefinedEffect.java           | 20 ++++++++++++++++++++
 .../compiler/typechecker/typesets/TypeSets.java      |  1 +
 6 files changed, 33 insertions(+), 29 deletions(-)
 delete mode 100644 src/main/java/org/shedlang/compiler/typechecker/errors/NotUserDefinedEffectError.java
 create mode 100644 src/main/java/org/shedlang/compiler/typechecker/typesets/TypeSetUserDefinedEffect.java

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/ast/typed/TypedTryNode.java b/src/main/java/org/shedlang/compiler/ast/typed/TypedTryNode.java
index 123744d5..5e87a6b7 100644
--- a/src/main/java/org/shedlang/compiler/ast/typed/TypedTryNode.java
+++ b/src/main/java/org/shedlang/compiler/ast/typed/TypedTryNode.java
@@ -1,14 +1,14 @@
 package org.shedlang.compiler.ast.typed;
 
 import org.shedlang.compiler.sources.Source;
-import org.shedlang.compiler.types.Effect;
 import org.shedlang.compiler.types.Type;
+import org.shedlang.compiler.types.UserDefinedEffect;
 
 import java.util.List;
 
 public record TypedTryNode(
     TypedBlockNode body,
-    TypedTypeLevelExpressionNode<Effect> handledEffect,
+    TypedTypeLevelExpressionNode<UserDefinedEffect> handledEffect,
     List<TypedTryHandlerMethodNode> handlerMethods,
     Source source
 ) implements TypedExpressionNode {
diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
index 5c203322..fdc24287 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -383,6 +383,13 @@ public class TypeChecker {
         return typeCheckTypeLevelExpression(TypeSets.EFFECT, untyped, context);
     }
 
+    private static TypedTypeLevelExpressionNode<UserDefinedEffect> typeCheckUserDefinedEffect(
+        UntypedTypeLevelExpressionNode untyped,
+        TypeCheckerContext context
+    ) {
+        return typeCheckTypeLevelExpression(TypeSets.USER_DEFINED_EFFECT, untyped, context);
+    }
+
     private static TypeCheckSteps<TypedEffectDefinitionNode> typeCheckStepsEffectDefinition(
         UntypedEffectDefinitionNode untyped
     ) {
@@ -1671,14 +1678,8 @@ public class TypeChecker {
         UntypedTryNode untyped,
         TypeCheckerContext context
     ) {
-        var typedHandledEffect = typeCheckEffect(untyped.handledEffect(), context);
-
-        if (!(typedHandledEffect.value() instanceof UserDefinedEffect handledEffect)) {
-            throw new NotUserDefinedEffectError(
-                typedHandledEffect.value(),
-                untyped.handledEffect().source()
-            );
-        }
+        var typedHandledEffect = typeCheckUserDefinedEffect(untyped.handledEffect(), context);
+        var handledEffect = typedHandledEffect.value();
 
         var declaredVariables = DeclaredVariables.forFunctionStatements(
             untyped.body().statements(),
diff --git a/src/main/java/org/shedlang/compiler/typechecker/errors/NotUserDefinedEffectError.java b/src/main/java/org/shedlang/compiler/typechecker/errors/NotUserDefinedEffectError.java
deleted file mode 100644
index a740dccc..00000000
--- a/src/main/java/org/shedlang/compiler/typechecker/errors/NotUserDefinedEffectError.java
+++ /dev/null
@@ -1,18 +0,0 @@
-package org.shedlang.compiler.typechecker.errors;
-
-import org.shedlang.compiler.errors.SourceError;
-import org.shedlang.compiler.sources.Source;
-import org.shedlang.compiler.types.Effect;
-
-public class NotUserDefinedEffectError extends SourceError {
-    private final Effect effect;
-
-    public NotUserDefinedEffectError(Effect effect, Source source) {
-        super("Only user-defined effects can be handled, but was: " + effect.describe(), source);
-        this.effect = effect;
-    }
-
-    public Effect effect() {
-        return effect;
-    }
-}
diff --git a/src/main/java/org/shedlang/compiler/typechecker/typesets/TypeSetTypeLevelValue.java b/src/main/java/org/shedlang/compiler/typechecker/typesets/TypeSetTypeLevelValue.java
index b9e66762..a0a6d43a 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/typesets/TypeSetTypeLevelValue.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/typesets/TypeSetTypeLevelValue.java
@@ -2,6 +2,6 @@ package org.shedlang.compiler.typechecker.typesets;
 
 import org.shedlang.compiler.types.TypeLevelValue;
 
-public sealed interface TypeSetTypeLevelValue<T extends TypeLevelValue> extends TypeSet permits TypeSetEffect, TypeSetMetaType, TypeSetStructMetaType {
+public sealed interface TypeSetTypeLevelValue<T extends TypeLevelValue> extends TypeSet permits TypeSetEffect, TypeSetMetaType, TypeSetStructMetaType, TypeSetUserDefinedEffect {
     Class<T> valueClass();
 }
diff --git a/src/main/java/org/shedlang/compiler/typechecker/typesets/TypeSetUserDefinedEffect.java b/src/main/java/org/shedlang/compiler/typechecker/typesets/TypeSetUserDefinedEffect.java
new file mode 100644
index 00000000..3ee46d2c
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/typechecker/typesets/TypeSetUserDefinedEffect.java
@@ -0,0 +1,20 @@
+package org.shedlang.compiler.typechecker.typesets;
+
+import org.shedlang.compiler.types.UserDefinedEffect;
+
+public final class TypeSetUserDefinedEffect implements TypeSetTypeLevelValue<UserDefinedEffect> {
+    private TypeSetUserDefinedEffect() {
+    }
+
+    static final TypeSetUserDefinedEffect INSTANCE = new TypeSetUserDefinedEffect();
+
+    @Override
+    public String describe() {
+        return "user-defined effect";
+    }
+
+    @Override
+    public Class<UserDefinedEffect> valueClass() {
+        return UserDefinedEffect.class;
+    }
+}
diff --git a/src/main/java/org/shedlang/compiler/typechecker/typesets/TypeSets.java b/src/main/java/org/shedlang/compiler/typechecker/typesets/TypeSets.java
index b6a0ad3a..57002c37 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/typesets/TypeSets.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/typesets/TypeSets.java
@@ -11,6 +11,7 @@ public class TypeSets {
     public static final TypeSetMetaType META_TYPE = TypeSetMetaType.INSTANCE;
     public static final TypeSetStructMetaType STRUCT_META_TYPE = TypeSetStructMetaType.INSTANCE;
     public static final TypeSetTuple TUPLE = TypeSetTuple.INSTANCE;
+    public static final TypeSetUserDefinedEffect USER_DEFINED_EFFECT = TypeSetUserDefinedEffect.INSTANCE;
 
     public static TypeSet type(Type type) {
         return new TypeSetType(type);
-- 
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