A few refinements and comments to add clarity.

slox/Interpreter.swift

@@ -125,12 +125,13 @@ class Interpreter {
             staticMethodImpls[nameToken.lexeme] = staticMethodImpl
         }
 
-        let metaclass = LoxClass(name: "\(nameToken.lexeme) metaclass" ,
-                                 methods: staticMethodImpls,
-                                 metaclass: nil)
-        let newClass = LoxClass(name: nameToken.lexeme,
-                                methods: methodImpls,
-                                metaclass: metaclass)
+        let newClass = LoxClass(name: nameToken.lexeme, methods: methodImpls)
+        if !staticMethodImpls.isEmpty {
+            // NOTA BENE: This assigns the static methods to the metaclass,
+            // which is lazily created in `LoxInstance`
+            newClass.klass.methods = staticMethodImpls
+        }
+
         try environment.assignAtDepth(name: nameToken.lexeme, value: .instance(newClass), depth: 0)
     }
 

slox/LoxClass.swift

@@ -16,10 +16,11 @@ class LoxClass: LoxInstance, LoxCallable {
     }
     var methods: [String: UserDefinedFunction]
 
-    init(name: String, methods: [String: UserDefinedFunction], metaclass: LoxClass?) {
+    init(name: String, methods: [String: UserDefinedFunction]) {
         self.name = name
         self.methods = methods
-        super.init(klass: metaclass)
+
+        super.init(klass: nil)
     }
 
     static func == (lhs: LoxClass, rhs: LoxClass) -> Bool {

slox/LoxInstance.swift

@@ -19,12 +19,15 @@ class LoxInstance: Equatable {
         if _klass == nil {
             // Only metaclasses should ever have a `nil` value for `_klass`
             let selfClass = self as! LoxClass
-            _klass = LoxClass(name: "\(selfClass.name) metaclass", methods: [:], metaclass: nil)
+            _klass = LoxClass(name: "\(selfClass.name) metaclass", methods: [:])
         }
         return _klass!
     }
     var properties: [String: LoxValue] = [:]
 
+    /// - Parameter klass: The class this instance belongs to.
+    /// Use `nil` if this instance *is* a class; the `klass` property
+    /// will then instantiate a metaclass for it on demand.
     init(klass: LoxClass?) {
         self._klass = klass
     }