Support accessing fields on effects

3 files changed, 30 insertions, 2 deletions

diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
index f86ed78f..db81d7cc 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -540,6 +540,15 @@ public class TypeChecker {
 
             return namespaceTypeInfo.fieldType(fieldName)
                 .orElseThrow(() -> new NoSuchFieldError(receiverTypeNamespace, fieldName, source));
+        } else if (
+            receiverType instanceof TypeLevelValueType receiverTypeTypeLevelValue &&
+            receiverTypeTypeLevelValue.value() instanceof UserDefinedEffect effect
+        ) {
+            var effectInfo = context.userDefinedEffectInfo(effect, source);
+
+            return effectInfo.fields().fieldType(fieldName)
+                .orElseThrow(() -> new NoSuchFieldError(receiverType, fieldName, source))
+                .withEffect(effect);
         } else {
             throw new NoSuchFieldError(receiverType, fieldName, source);
         }
diff --git a/src/main/java/org/shedlang/compiler/types/FunctionType.java b/src/main/java/org/shedlang/compiler/types/FunctionType.java
index 285dadf8..e217fbd4 100644
--- a/src/main/java/org/shedlang/compiler/types/FunctionType.java
+++ b/src/main/java/org/shedlang/compiler/types/FunctionType.java
@@ -4,8 +4,6 @@ import org.pcollections.Empty;
 import org.pcollections.PVector;
 
 import java.util.List;
-import java.util.Set;
-import java.util.stream.Collectors;
 
 import static org.shedlang.compiler.util.Iterables.forEachInterspersed;
 
@@ -54,6 +52,15 @@ public record FunctionType(
         return description.toString();
     }
 
+    public FunctionType withEffect(Effect effect) {
+        return new FunctionType(
+            this.positionalParams,
+            this.namedParams,
+            effect,
+            this.returnType
+        );
+    }
+
     public static Builder builder() {
         return new Builder(Empty.vector(), Empty.vector(), Effects.NONE, Types.UNIT);
     }
diff --git a/src/main/java/org/shedlang/compiler/types/UserDefinedEffectInfo.java b/src/main/java/org/shedlang/compiler/types/UserDefinedEffectInfo.java
index a36b85a6..1785d22b 100644
--- a/src/main/java/org/shedlang/compiler/types/UserDefinedEffectInfo.java
+++ b/src/main/java/org/shedlang/compiler/types/UserDefinedEffectInfo.java
@@ -1,5 +1,17 @@
 package org.shedlang.compiler.types;
 
 public record UserDefinedEffectInfo(FieldsInfo<FunctionType> fields) {
+    public static Builder builder() {
+        return new Builder(FieldsInfo.builder());
+    }
 
+    public record Builder(FieldsInfo.Builder<FunctionType> fields) {
+        public UserDefinedEffectInfo build() {
+            return new UserDefinedEffectInfo(fields.build());
+        }
+
+        public Builder addField(String name, FunctionType type) {
+            return new Builder(this.fields.addField(name, type));
+        }
+    }
 }