add shortcuts for quasiquote and unquote

src/Reader.php

@@ -16,12 +16,11 @@ class Reader
     private function readForm(array $tokens, int &$index)
     {
         if ($tokens[$index] == "'") {
-            $index++;
+            return $this->readSpecialForm($tokens, $index, 'quote');
-            $contents = [new Symbol('quote')];
+        } elseif ($tokens[$index] == "`") {
-            if ($index < count($tokens) && !in_array($tokens[$index], [')', ']', '}'])) {
+            return $this->readSpecialForm($tokens, $index, 'quasiquote');
-                $contents[] = $this->readForm($tokens, $index);
+        } elseif ($tokens[$index] == "~") {
-            }
+            return $this->readSpecialForm($tokens, $index, 'unquote');
-            return new MList($contents);
         } elseif ($tokens[$index] == '(') {
             return $this->readList($tokens, $index);
         } elseif ($tokens[$index] == '[') {
@@ -33,6 +32,16 @@ class Reader
         }
     }
 
+    private function readSpecialForm(array $tokens, int &$index, string $symbol)
+    {
+        $index++;
+        $contents = [new Symbol($symbol)];
+        if ($index < count($tokens) && !in_array($tokens[$index], [')', ']', '}'])) {
+            $contents[] = $this->readForm($tokens, $index);
+        }
+        return new MList($contents);
+    }
+
     private function readList(array $tokens, int &$index): MList
     {
         return new MList($this->readCollection($tokens, $index, ')'));

src/Tokenizer.php

@@ -69,7 +69,7 @@ class Tokenizer
                     $addCurrent();
                     $tokens[] = $c;
                     $parens[$parenIndexes[$c]]--;
-                } elseif ($c == "'") {
+                } elseif ($c == "'" || $c == "`" || $c == "~") {
                     // Other special characters
                     $addCurrent();
                     $tokens[] = $c;