More type stuff and unused code removed.

src/FactorGraphs/DefaultVariable.php

@@ -1,24 +0,0 @@
-<?php
-
-namespace DNW\Skills\FactorGraphs;
-
-use Exception;
-
-// XXX: This class is not used anywhere
-class DefaultVariable extends Variable
-{
-    public function __construct()
-    {
-        parent::__construct('Default', null);
-    }
-
-    public function getValue()
-    {
-        return null;
-    }
-
-    public function setValue($value): never
-    {
-        throw new Exception();
-    }
-}

src/FactorGraphs/Factor.php

@@ -102,7 +102,7 @@ abstract class Factor implements \Stringable
 
     abstract public function createVariableToMessageBinding(Variable $variable);
 
-    protected function createVariableToMessageBindingWithMessage(Variable $variable, Message $message)
+    protected function createVariableToMessageBindingWithMessage(Variable $variable, Message $message): Message
     {
         $this->_messageToVariableBinding->setValue($message, $variable);
         $this->_messages[] = $message;

src/FactorGraphs/KeyedVariable.php

@@ -4,12 +4,12 @@ namespace DNW\Skills\FactorGraphs;
 
 class KeyedVariable extends Variable
 {
-    public function __construct(private $_key, $name, $prior)
+    public function __construct(private mixed $_key, string $name, mixed $prior)
     {
         parent::__construct($name, $prior);
     }
 
-    public function getKey()
+    public function getKey(): mixed
     {
         return $this->_key;
     }

src/FactorGraphs/Variable.php

@@ -24,7 +24,7 @@ class Variable implements \Stringable
         $this->_value = $value;
     }
 
-    public function resetToPrior()
+    public function resetToPrior(): void
     {
         $this->_value = $this->_prior;
     }

src/FactorGraphs/VariableFactory.php

@@ -8,14 +8,14 @@ class VariableFactory
     {
     }
 
-    public function createBasicVariable($name)
+    public function createBasicVariable(string $name): Variable
     {
         $initializer = $this->_variablePriorInitializer;
 
         return new Variable($name, $initializer());
     }
 
-    public function createKeyedVariable($key, $name)
+    public function createKeyedVariable(mixed $key, string $name): KeyedVariable
     {
         $initializer = $this->_variablePriorInitializer;