Check call effect is sub-effect of function effect

4 files changed, 61 insertions, 7 deletions

diff --git a/src/main/java/org/shedlang/compiler/ShedCompiler.java b/src/main/java/org/shedlang/compiler/ShedCompiler.java
index d727aea5..8f63ce75 100644
--- a/src/main/java/org/shedlang/compiler/ShedCompiler.java
+++ b/src/main/java/org/shedlang/compiler/ShedCompiler.java
@@ -46,7 +46,7 @@ public class ShedCompiler {
                     Types.UNIT
                 ))
             ))
-            .enter(P.map(
+            .enterBlock(P.map(
                 Map.entry("Io", Types.effectType(Effects.IO)),
                 Map.entry("Unit", Types.metaType(Types.UNIT)),
 
diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
index 591d4810..3b128801 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -28,6 +28,10 @@ public class TypeChecker {
         }
     }
 
+    private static boolean isSubEffect(Effect subEffect, Effect superEffect, TypeCheckerContext context) {
+        return subEffect.equals(superEffect);
+    }
+
     private static boolean isSubType(Type subType, Type superType, TypeCheckerContext context) {
         return subType.equals(superType);
     }
@@ -152,10 +156,18 @@ public class TypeChecker {
             throw new FunctionHasNoEffectsError(untyped.source());
         }
 
+        if (!isSubEffect(receiverType.effect(), context.effect(), context)) {
+            throw new UnexpectedEffectError(
+                context.effect(),
+                receiverType.effect(),
+                untyped.source()
+            );
+        }
+
         return context.toResult(new TypedCallNode(
             typedReceiver,
             typedArgs,
-            false,
+            untyped.hasEffects(),
             receiverType.returnType(),
             untyped.source()
         ));
@@ -220,7 +232,7 @@ public class TypeChecker {
         var bodyEnvironment = typedParams.all()
             .map(param -> Map.entry(param.name(), param.type().value()))
             .collect(PCollectors.toMap());
-        var bodyContext = context.enter(bodyEnvironment);
+        var bodyContext = context.enterFunction(bodyEnvironment, typedEffect.map(e -> e.value()).orElse(Effects.NONE));
 
         var bodyResult = bodyContext.mapWithContext(
             untyped.body(),
diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeCheckerContext.java b/src/main/java/org/shedlang/compiler/typechecker/TypeCheckerContext.java
index 69080884..71a02101 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeCheckerContext.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeCheckerContext.java
@@ -3,9 +3,7 @@ package org.shedlang.compiler.typechecker;
 import org.pcollections.Empty;
 import org.pcollections.PMap;
 import org.shedlang.compiler.ast.typed.FreeVariables;
-import org.shedlang.compiler.types.NamespaceName;
-import org.shedlang.compiler.types.NamespaceTypeInfo;
-import org.shedlang.compiler.types.Type;
+import org.shedlang.compiler.types.*;
 import org.shedlang.compiler.util.POrderedMap;
 
 import java.util.ArrayList;
@@ -17,35 +15,49 @@ import java.util.function.BiFunction;
 public class TypeCheckerContext {
     public static final TypeCheckerContext EMPTY = new TypeCheckerContext(
         Empty.map(),
+        Effects.NONE,
         Set.of(),
         FreeVariables.builder(),
         Empty.map()
     );
 
     private final PMap<String, Type> environment;
+    private final Effect effect;
     private final Set<String> boundVariables;
     private final FreeVariables.Builder freeVariables;
     private final PMap<NamespaceName, NamespaceTypeInfo> namespaceTypeInfo;
 
     public TypeCheckerContext(
         PMap<String, Type> environment,
+        Effect effect,
         Set<String> boundVariables,
         FreeVariables.Builder freeVariables,
         PMap<NamespaceName, NamespaceTypeInfo> namespaceTypeInfo
     ) {
         this.environment = environment;
+        this.effect = effect;
         this.boundVariables = boundVariables;
         this.freeVariables = freeVariables;
         this.namespaceTypeInfo = namespaceTypeInfo;
     }
 
-    public TypeCheckerContext enter(PMap<String, Type> environment) {
+    public TypeCheckerContext enterBlock(PMap<String, Type> environment) {
+        return enter(environment, this.effect);
+    }
+
+    public TypeCheckerContext enterFunction(PMap<String, Type> environment, Effect effect) {
+        return enter(environment, effect);
+    }
+
+    private TypeCheckerContext enter(PMap<String, Type> environment, Effect effect) {
         return new TypeCheckerContext(
             this.environment.plusAll(environment),
+            effect,
             environment.keySet(),
             FreeVariables.builder(),
             this.namespaceTypeInfo
         );
+
     }
 
     public TypeCheckerResult<Optional<Type>> runtimeLookup(String name) {
@@ -58,10 +70,15 @@ public class TypeCheckerContext {
     public Optional<Type> compileTimeLookup(String name) {
         return Optional.ofNullable(environment.get(name));
     }
+
+    public Effect effect() {
+        return effect;
+    }
     
     private TypeCheckerContext withFreeVariable(String name) {
         return new TypeCheckerContext(
             environment,
+            this.effect,
             boundVariables,
             freeVariables.plus(name),
             this.namespaceTypeInfo
@@ -80,6 +97,7 @@ public class TypeCheckerContext {
 
         return new TypeCheckerContext(
             this.environment,
+            this.effect,
             this.boundVariables,
             this.freeVariables,
             this.namespaceTypeInfo.plus(namespaceName, namespaceTypeInfo)
diff --git a/src/main/java/org/shedlang/compiler/typechecker/errors/UnexpectedEffectError.java b/src/main/java/org/shedlang/compiler/typechecker/errors/UnexpectedEffectError.java
new file mode 100644
index 00000000..3b617207
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/typechecker/errors/UnexpectedEffectError.java
@@ -0,0 +1,24 @@
+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 UnexpectedEffectError extends SourceError {
+    private final Effect allowed;
+    private final Effect actual;
+
+    public UnexpectedEffectError(Effect allowed, Effect actual, Source source) {
+        super("Allowed effect is " + allowed.describe() + " but was " + actual.describe(), source);
+        this.allowed = allowed;
+        this.actual = actual;
+    }
+
+    public Effect allowed() {
+        return allowed;
+    }
+
+    public Effect actual() {
+        return actual;
+    }
+}