Much more progress, still doesn't compile.

src/c/payloads/exception.c

@@ -0,0 +1,13 @@
+
+
+#import "memory/pointer.h"
+#import "memory/pso.h"
+#import "payloads/exception.h"
+
+/**
+ * @param p a pointer to an object.
+ * @return true if that object is an exception, else false.
+ */
+bool exceptionp( struct pso_pointer p) {
+	return (get_tag_value( p) == EXCEPTIONTV);
+}

src/c/payloads/exception.h

@@ -9,6 +9,7 @@
 
 #ifndef __psse_payloads_exception_h
 #define __psse_payloads_exception_h
+#include <stdbool.h>
 
 #include "memory/pointer.h"
 
@@ -27,5 +28,6 @@ struct exception_payload {
     struct pso_pointer cause;
 };
 
+bool exceptionp( struct pso_pointer p);
 
 #endif

src/c/payloads/stack.h

@@ -13,6 +13,7 @@
 #define __psse_payloads_stack_h
 
 #include "memory/pointer.h"
+#include "memory/pso4.h"
 
 #define STACKTAG "STK"
 #define STACKTV  4936787
@@ -47,4 +48,6 @@ struct stack_frame_payload {
     uint32_t depth;
 };
 
+struct pso_pointer fetch_arg( struct pso4 *frame, unsigned int index );
+
 #endif

src/c/payloads/vector_pointer.c

@@ -0,0 +1,18 @@
+/**
+ *  payloads/vector_pointer.c
+ *
+ *  A pointer to an object in vector space.
+ *
+ *  (c) 2026 Simon Brooke <simon@journeyman.cc>
+ *  Licensed under GPL version 2.0, or, at your option, any later version.
+ */
+
+#include <stdbool.h>
+
+#include "memory/pointer.h"
+#include "memory/pso.h"
+#include "payloads/vector_pointer.h"
+
+bool vectorpointp( struct pso_pointer p) {
+	return (get_tag_value( p) == VECTORPOINTTV);
+}

src/c/payloads/vector_pointer.h

@@ -10,6 +10,8 @@
 #ifndef __psse_payloads_vector_pointer_h
 #define __psse_payloads_vector_pointer_h
 
+#include <stdbool.h>
+
 #include "memory/pointer.h"
 
 /**
@@ -37,4 +39,6 @@ struct vectorp_payload {
     void *address;
 };
 
+bool vectorpointp( struct pso_pointer p);
+
 #endif