Got most of the new memory architecture roughed out.

src/c/payloads/symbol.h

@@ -0,0 +1,25 @@
+/**
+ *  payloads/symbol.h
+ *
+ *  A symbol cell.
+ *
+ *  (c) 2026 Simon Brooke <simon@journeyman.cc>
+ *  Licensed under GPL version 2.0, or, at your option, any later version.
+ */
+
+#ifndef __psse_payloads_symbol_h
+#define __psse_payloads_symbol_h
+
+#include "memory/pointer.h"
+
+
+/**
+ * Tag for a symbol: just like a keyword except not self-evaluating.
+ */
+#define SYMBOLTAG   "SYM"
+
+/* TODO: for now, Symbol shares a payload with String, but this may change.
+ * Strings are of indefinite length, but symbols are really not, and might
+ * fit into any size class. */
+
+#endif