Extract isMutable() methods

3 files changed, 20 insertions, 14 deletions

diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
index e9dec032..9963ee56 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -644,19 +644,11 @@ public class TypeChecker {
                     freeVariable.firstReferenceSource()
                 ));
 
-            if (!signature.isEffectHandlerMethod()) {
-                switch (variable.variableType()) {
-                    case CONSTANT -> {}
-                    case IMPORT -> {}
-                    case PARAM -> {}
-                    case VAL -> {}
-
-                    case VAR ->
-                        throw new CannotCaptureVarError(
-                            freeVariable.name(),
-                            freeVariable.firstReferenceSource()
-                        );
-                };
+            if (!signature.isEffectHandlerMethod() && variable.isMutable()) {
+                throw new CannotCaptureVarError(
+                    freeVariable.name(),
+                    freeVariable.firstReferenceSource()
+                );
             }
         }
 
diff --git a/src/main/java/org/shedlang/compiler/typechecker/Variable.java b/src/main/java/org/shedlang/compiler/typechecker/Variable.java
index fc06acc9..264942a8 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/Variable.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/Variable.java
@@ -16,4 +16,8 @@ public record Variable(Optional<Type> type, VariableType variableType) {
     public boolean hasType() {
         return type.isPresent();
     }
+
+    public boolean isMutable() {
+        return variableType.isMutable();
+    }
 }
diff --git a/src/main/java/org/shedlang/compiler/typechecker/VariableType.java b/src/main/java/org/shedlang/compiler/typechecker/VariableType.java
index 64652060..a6cd12df 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/VariableType.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/VariableType.java
@@ -5,5 +5,15 @@ public enum VariableType {
     IMPORT,
     PARAM,
     VAL,
-    VAR,
+    VAR;
+
+    boolean isMutable() {
+        return switch (this) {
+            case CONSTANT -> false;
+            case IMPORT -> false;
+            case PARAM -> false;
+            case VAL -> false;
+            case VAR -> true;
+        };
+    }
 }