Store whether bound variable is mutable or not

3 files changed, 17 insertions, 12 deletions

diff --git a/src/main/java/org/shedlang/compiler/ast/typed/BoundVariable.java b/src/main/java/org/shedlang/compiler/ast/typed/BoundVariable.java
index dcd2d113..f2c76c06 100644
--- a/src/main/java/org/shedlang/compiler/ast/typed/BoundVariable.java
+++ b/src/main/java/org/shedlang/compiler/ast/typed/BoundVariable.java
@@ -1,7 +1,11 @@
 package org.shedlang.compiler.ast.typed;
 
-public record BoundVariable(String name) {
+public record BoundVariable(String name, boolean isMutable) {
     public static BoundVariable immutable(String name) {
-        return new BoundVariable(name);
+        return new BoundVariable(name, false);
+    }
+
+    public static BoundVariable mutable(String name) {
+        return new BoundVariable(name, true);
     }
 }
diff --git a/src/main/java/org/shedlang/compiler/typechecker/EnvironmentBuilder.java b/src/main/java/org/shedlang/compiler/typechecker/EnvironmentBuilder.java
index 85292f8c..6a5e32a2 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/EnvironmentBuilder.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/EnvironmentBuilder.java
@@ -2,6 +2,7 @@ package org.shedlang.compiler.typechecker;
 
 import org.pcollections.Empty;
 import org.pcollections.PMap;
+import org.shedlang.compiler.ast.typed.BoundVariable;
 import org.shedlang.compiler.sources.Source;
 import org.shedlang.compiler.typechecker.errors.DuplicateVariableNameError;
 
@@ -46,7 +47,9 @@ public class EnvironmentBuilder {
         return environment;
     }
 
-    public List<String> names() {
-        return environment.keySet().stream().toList();
+    public List<BoundVariable> toBoundVariables() {
+        return environment.entrySet().stream()
+            .map(entry -> new BoundVariable(entry.getKey(), entry.getValue().isMutable()))
+            .toList();
     }
 }
diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
index 1ea3b680..27210ec5 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -213,7 +213,7 @@ public class TypeChecker {
 
     private static TypeCheckerResult<TypedBlockNode> typeCheckBlock(
         UntypedBlockNode untyped,
-        List<String> declaredVariableNames,
+        List<BoundVariable> declaredVariables,
         TypeCheckerContext context
     ) {
         var typedStatementsResult = context.mapWithContext(
@@ -225,9 +225,7 @@ public class TypeChecker {
 
         var typed = new TypedBlockNode(
             typedStatements,
-            declaredVariableNames.stream()
-                .map(BoundVariable::new)
-                .toList(),
+            declaredVariables,
             untyped.source()
         );
 
@@ -246,7 +244,7 @@ public class TypeChecker {
 
         context = context.enterBlock(bodyEnvironment.build());
 
-        var typedBodyResult = typeCheckBlock(untyped, bodyEnvironment.names(), context);
+        var typedBodyResult = typeCheckBlock(untyped, bodyEnvironment.toBoundVariables(), context);
         var typedBody = typedBodyResult.value();
         context = typedBodyResult.context();
 
@@ -584,7 +582,7 @@ public class TypeChecker {
             signature.returnTypeState()
         );
 
-        var bodyResult = typeCheckBlock(untyped, bodyEnvironment.names(), context);
+        var bodyResult = typeCheckBlock(untyped, bodyEnvironment.toBoundVariables(), context);
         var typedBody = bodyResult.value();
         context = bodyResult.context();
 
@@ -1684,7 +1682,7 @@ public class TypeChecker {
 
         context = context.enterTryBody(bodyEnvironment.build(), typedHandledEffect.value());
 
-        var typedBodyResult = typeCheckBlock(untyped.body(), bodyEnvironment.names(), context);
+        var typedBodyResult = typeCheckBlock(untyped.body(), bodyEnvironment.toBoundVariables(), context);
         var typedBody = typedBodyResult.value();
         context = typedBodyResult.context();
 
@@ -1907,7 +1905,7 @@ public class TypeChecker {
             context = context.updateType(variableName.get(), typedCaseType.value(), untyped.source());
         }
 
-        var typedBodyResult = typeCheckBlock(untyped.body(), bodyEnvironment.names(), context);
+        var typedBodyResult = typeCheckBlock(untyped.body(), bodyEnvironment.toBoundVariables(), context);
         var typedBody = typedBodyResult.value();
         context = typedBodyResult.context();