1 files changed, 13 insertions, 14 deletions
diff --git a/src/main/java/org/zwobble/couscous/values/StringValue.java b/src/main/java/org/zwobble/couscous/values/StringValue.java
index 3f4b2b0..da45f02 100644
--- a/src/main/java/org/zwobble/couscous/values/StringValue.java
+++ b/src/main/java/org/zwobble/couscous/values/StringValue.java
@@ -1,26 +1,25 @@
 package org.zwobble.couscous.values;
 
-import java.util.Optional;
-
 import lombok.Value;
 import lombok.val;
 
 @Value
 public class StringValue implements InterpreterValue {
+    private static final ConcreteType<?> TYPE = ConcreteType.<StringValue>builder()
+        .method("length", (receiver, arguments) -> new IntegerValue(receiver.value.length()))
+        
+        .method("substring", (receiver, arguments) -> {
+            val startIndex = arguments.pop(IntegerValue.class);
+            val endIndex = arguments.pop(IntegerValue.class);
+            return new StringValue(receiver.value.substring(startIndex.getValue(), endIndex.getValue()));
+        })
+        
+        .build();
+    
     String value;
 
     @Override
-    public Optional<MethodValue> getMethod(String methodName) {
-        if (methodName == "length") {
-            return Optional.of(arguments -> new IntegerValue(value.length()));
-        } else if (methodName == "substring") {
-            return Optional.of(arguments -> {
-                val startIndex = (IntegerValue)arguments.get(0);
-                val endIndex = (IntegerValue)arguments.get(1);
-                return new StringValue(value.substring(startIndex.getValue(), endIndex.getValue()));
-            });
-        } else {
-            return Optional.empty();
-        }
+    public ConcreteType<?> getType() {
+        return TYPE;
     }
 }