read isn't written yet, but I think all the building blocks I need for it are.

Compiles and runs; does nothing yet.

src/c/memory/page.c

@@ -152,3 +152,11 @@ struct pso_pointer allocate_page( uint8_t size_class ) {
 
     return result;
 }
+
+/**
+ * @brief allow other files to see the current value of npages_allocated, but not
+ * change it.
+ */
+uint32_t get_pages_allocated() {
+	return npages_allocated;
+}

src/c/memory/page.h

@@ -74,4 +74,6 @@ union page {
 
 struct pso_pointer allocate_page( uint8_t size_class );
 
+uint32_t get_pages_allocated();
+
 #endif

src/c/memory/pointer.c

@@ -41,8 +41,13 @@ struct pso2 *pointer_to_object( struct pso_pointer pointer ) {
     struct pso2 *result = NULL;
 
     if ( pointer.node == node_index ) {
-        union page *pg = pages[pointer.page];
-        result = ( struct pso2 * ) &pg->words[pointer.offset];
+    	if (pointer.page < get_pages_allocated() && pointer.offset < (PAGE_BYTES / 8)) {
+    		// TODO: that's not really a safe test of whether this is a valid pointer.
+			union page *pg = pages[pointer.page];
+			result = ( struct pso2 * ) &pg->words[pointer.offset];
+    	} else {
+    		// TODO: throw bad pointer exception.
+    	}
     }
     // TODO: else if we have a copy of the object in cache, return that;
     // else request a copy of the object from the node which curates it.

src/c/memory/pso2.h

@@ -12,6 +12,7 @@
 
 #include <stdint.h>
 
+#include "../payloads/psse_string.h"
 #include "memory/header.h"
 #include "payloads/character.h"
 #include "payloads/cons.h"
@@ -22,7 +23,6 @@
 #include "payloads/lambda.h"
 #include "payloads/nlambda.h"
 #include "payloads/read_stream.h"
-#include "payloads/psse-string.h"
 #include "payloads/symbol.h"
 #include "payloads/time.h"
 #include "payloads/vector_pointer.h"

src/c/ops/eq.c

@@ -3,7 +3,7 @@
  *
  *  Post Scarcity Software Environment: eq.
  *
- *  Test for pointer equality.
+ *  Test for pointer equality; bootstrap level tests for object equality.
  *
  *  (c) 2026 Simon Brooke <simon@journeyman.cc>
  *  Licensed under GPL version 2.0, or, at your option, any later version.
@@ -12,6 +12,11 @@
 #include "memory/memory.h"
 #include "memory/node.h"
 #include "memory/pointer.h"
+#include "memory/pso2.h"
+#include "memory/tags.h"
+
+#include "payloads/cons.h"
+#include "payloads/integer.h"
 #include "payloads/stack.h"
 #include "ops/stack_ops.h"
 #include "ops/truth.h"
@@ -32,6 +37,39 @@ bool eq( struct pso_pointer a, struct pso_pointer b ) {
     return ( a.node == b.node && a.page == b.page && a.offset == b.offset );
 }
 
+bool equal( struct pso_pointer a, struct pso_pointer b) {
+	bool result = false;
+
+	if ( eq( a, b)) {
+		result = true;
+	} else if ( get_tag_value(a) == get_tag_value(b)) {
+		switch ( get_tag_value(a)) {
+		case CONSTV :
+			result = (equal( car(a), car(b)) && equal( cdr(a), cdr(b)));
+			break;
+		case INTEGERTV :
+			result = (pointer_to_object(a)->payload.integer.value ==
+					pointer_to_object(b)->payload.integer.value);
+			break;
+		case KEYTV:
+		case STRINGTV :
+		case SYMBOLTV :
+			while (result == false && !nilp(a) && !nilp(b)) {
+				if (pointer_to_object(a)->payload.string.character ==
+						pointer_to_object(b)->payload.string.character) {
+					a = cdr(a);
+					b = cdr(b);
+				}
+			}
+			result = nilp(a) && nilp(b);
+			break;
+		}
+	}
+
+	return result;
+}
+
+
 /**
  * Function; do all arguments to this finction point to the same object? 
  *
@@ -60,3 +98,5 @@ struct pso_pointer lisp_eq( struct pso4 *frame,
 
     return result;
 }
+
+

src/c/ops/eq.h

@@ -22,4 +22,5 @@ struct pso_pointer lisp_eq( struct pso4 *frame,
                             struct pso_pointer frame_pointer,
                             struct pso_pointer env );
 
+bool equal( struct pso_pointer a, struct pso_pointer b);
 #endif

src/c/payloads/cons.c

@@ -14,7 +14,11 @@
 #include "memory/pso.h"
 #include "memory/pso2.h"
 #include "memory/tags.h" 
+
 #include "payloads/cons.h"
+#include "payloads/exception.h"
+
+#include "ops/string_ops.h"
 
 /**
  * @brief allocate a cons cell with this car and this cdr, and return a pointer
@@ -58,19 +62,29 @@ struct pso_pointer car( struct pso_pointer cons ) {
 }
 
 /**
- * @brief return the cdr of this cons cell.
+ * @brief return the cdr of this cons (or other sequence) cell.
  * 
  * @param cons a pointer to the cell.
  * @return the cdr of the indicated cell.
  * @exception if the pointer does not indicate a cons cell.
  */
-struct pso_pointer cdr( struct pso_pointer cons ) {
+struct pso_pointer cdr( struct pso_pointer p ) {
     struct pso_pointer result = nil;
     struct pso2 *object = pointer_to_object( result );
 
-    if ( consp( cons ) ) {
-        result = object->payload.cons.cdr;
+    switch (get_tag_value( p)) {
+    case CONSTV : result = object->payload.cons.cdr; break;
+    case KEYTV :
+    case STRINGTV :
+    case SYMBOLTV :
+    	result = object->payload.string.cdr; break;
+    default :
+    	result = make_exception(
+    			cons(c_string_to_lisp_string(L"Invalid type for cdr"), p),
+				nil, nil);
+    	break;
     }
+
     // TODO: else throw an exception
 
     return result;

src/c/payloads/exception.h

@@ -24,6 +24,7 @@ struct exception_payload {
     struct pso_pointer cause;
 };
 
-struct pso_pointer make_exception( struct pso_pointer message, struct pso_pointer frame_pointer, struct pso_pointer cause);
+struct pso_pointer make_exception( struct pso_pointer message,
+		struct pso_pointer frame_pointer, struct pso_pointer cause);
 
 #endif

src/c/payloads/stack.h

@@ -37,4 +37,6 @@ struct stack_frame_payload {
     uint32_t depth;
 };
 
+struct pso_pointer make_frame( struct pso_pointer previous, ...);
+
 #endif