My monster, it not only compiles, it now runs!

Makefile

@@ -8,8 +8,9 @@ DEPS := $(OBJS:.o=.d)
 
 TESTS := $(shell find unit-tests -name *.sh)
 
-INC_DIRS := $(shell find $(SRC_DIRS) -type d)
+# INC_DIRS := $(shell find $(SRC_DIRS) -type d)
-INC_FLAGS := $(addprefix -I,$(INC_DIRS))
+# INC_FLAGS := $(addprefix -I,$(INC_DIRS))
+INC_FLAGS := -I $(SRC_DIRS)
 
 TMP_DIR ?= ./tmp
 

src/c/memory/page.c

@@ -56,7 +56,8 @@ uint32_t npages_allocated = 0;
  * @return struct pso_pointer the new head for the freelist for this size_class,
  */
 struct pso_pointer initialise_page( union page *page_addr, uint16_t page_index,
-    uint8_t size_class, struct pso_pointer freelist) {
+                                    uint8_t size_class,
+                                    struct pso_pointer freelist ) {
     struct pso_pointer result = freelist;
     int obj_size = pow( 2, size_class );
     int obj_bytes = obj_size * sizeof( uint64_t );
@@ -67,13 +68,17 @@ struct pso_pointer initialise_page( union page* page_addr, uint16_t page_index,
     // `nil` and the next on for `t`.
     for ( int i = objs_in_page - 1; i >= 0; i-- ) {
         // it should be safe to cast any pso object to a pso2
-        struct pso2* object = (struct pso2 *)(page_addr + (i * obj_bytes)); 
+        struct pso2 *object =
+            ( struct pso2 * ) ( page_addr + ( i * obj_bytes ) );
 
         object->header.tag.bytes.size_class = size_class;
-        strncpy( &(object->header.tag.bytes.mnemonic[0]), FREETAG, TAGLENGTH);
+        strncpy( &( object->header.tag.bytes.mnemonic[0] ), FREETAG,
+                 TAGLENGTH );
         object->payload.free.next = result;
 
-        result = make_pointer( node_index, page_index, (uint16_t)( i * obj_size));
+        result =
+            make_pointer( node_index, page_index,
+                          ( uint16_t ) ( i * obj_size ) );
     }
 
     return result;
@@ -108,12 +113,12 @@ struct pso_pointer allocate_page( uint8_t size_class ) {
                               npages_allocated, size_class );
 
                 freelists[size_class] =
-                    initialise_page( (union page*)pg, npages_allocated, size_class, freelists[size_class] );
+                    initialise_page( ( union page * ) pg, npages_allocated,
+                                     size_class, freelists[size_class] );
 
                 debug_printf( DEBUG_ALLOC, 0,
                               L"Initialised page %d; freelist for size class %x updated.\n",
-                    npages_allocated,
+                              npages_allocated, size_class );
-                    size_class);    
 
                 npages_allocated++;
             } else {

src/c/memory/pointer.c

@@ -22,7 +22,8 @@
  * @param offset The offset, in words, within that page, of the object.
  * @return struct pso_pointer a pointer referencing the specified object.
  */
-struct pso_pointer make_pointer( uint32_t node, uint16_t page, uint16_t offset) {
+struct pso_pointer make_pointer( uint32_t node, uint16_t page,
+                                 uint16_t offset ) {
     return ( struct pso_pointer ) { node, page, offset };
 }
 
@@ -48,4 +49,3 @@ struct pso2* pointer_to_object( struct pso_pointer pointer) {
 
     return result;
 }
-

src/c/memory/pso.c

@@ -46,7 +46,8 @@ struct pso_pointer allocate( char* tag, uint8_t size_class) {
             struct pso2 *object = pointer_to_object( result );
             freelists[size_class] = object->payload.free.next;
 
-            strncpy( (char *)(object->header.tag.bytes.mnemonic), tag, TAGLENGTH);
+            strncpy( ( char * ) ( object->header.tag.bytes.mnemonic ), tag,
+                     TAGLENGTH );
 
             /* the object ought already to have the right size class in its tag
              * because it was popped off the freelist for that size class. */
@@ -67,7 +68,8 @@ struct pso_pointer allocate( char* tag, uint8_t size_class) {
 
 uint32_t payload_size( struct pso2 *object ) {
     // TODO: Unit tests DEFINITELY needed!
-	return ((1 << object->header.tag.bytes.size_class) - sizeof( struct pso_header));
+    return ( ( 1 << object->header.tag.bytes.size_class ) -
+             sizeof( struct pso_header ) );
 }
 
 void free_cell( struct pso_pointer p ) {
@@ -75,7 +77,8 @@ void free_cell( struct pso_pointer p) {
     uint32_t array_size = payload_size( p2 );
     uint8_t size_class = p2->header.tag.bytes.size_class;
 
-    strncpy( (char *)(p2->header.tag.bytes.mnemonic), FREETAG, TAGLENGTH);
+    strncpy( ( char * ) ( p2->header.tag.bytes.mnemonic ), FREETAG,
+             TAGLENGTH );
 
     /* will C just let me cheerfully walk off the end of the array I've declared? */
     for ( int i = 0; i < array_size; i++ ) {
@@ -103,12 +106,13 @@ struct pso_pointer inc_ref( struct pso_pointer pointer ) {
 #ifdef DEBUG
         debug_printf( DEBUG_ALLOC, 0,
                       L"\nIncremented object of type %3.3s at page %u, offset %u to count %u",
-                      ( ( char * ) &object->header.tag.bytes.mnemonic[0] ), pointer.page,
+                      ( ( char * ) &object->header.tag.bytes.mnemonic[0] ),
-                      pointer.offset, object->header.count );
+                      pointer.page, pointer.offset, object->header.count );
         if ( vectorpointp( pointer ) ) {
             debug_printf( DEBUG_ALLOC, 0,
                           L"; pointer to vector object of type %3.3s.\n",
-                          ( ( char * ) &( object->payload.vectorp.tag.bytes[0] ) ) );
+                          ( ( char * )
+                            &( object->payload.vectorp.tag.bytes[0] ) ) );
         } else {
             debug_println( DEBUG_ALLOC );
         }
@@ -134,12 +138,13 @@ struct pso_pointer dec_ref( struct pso_pointer pointer ) {
 #ifdef DEBUG
         debug_printf( DEBUG_ALLOC, 0,
                       L"\nDecremented object of type %4.4s at page %d, offset %d to count %d",
-                      ( ( char * ) (object->header.tag.bytes.mnemonic )), pointer.page,
+                      ( ( char * ) ( object->header.tag.bytes.mnemonic ) ),
-                      pointer.offset, object->header.count );
+                      pointer.page, pointer.offset, object->header.count );
         if ( vectorpointp( pointer ) ) {
             debug_printf( DEBUG_ALLOC, 0,
                           L"; pointer to vector object of type %3.3s.\n",
-                          ( ( char * ) &( object->payload.vectorp.tag.bytes ) ) );
+                          ( ( char * )
+                            &( object->payload.vectorp.tag.bytes ) ) );
         } else {
             debug_println( DEBUG_ALLOC );
         }

src/c/ops/eq.c

@@ -13,6 +13,7 @@
 #include "memory/node.h"
 #include "memory/pointer.h"
 #include "payloads/stack.h"
+#include "ops/stack_ops.h"
 #include "ops/truth.h"
 
 /**
@@ -48,9 +49,12 @@ struct pso_pointer lisp_eq( struct pso4 *frame,
                             struct pso_pointer env ) {
     struct pso_pointer result = t;
 
-    if ( frame->args > 1 ) {
+    if ( frame->payload.stack_frame.args > 1 ) {
-        for ( int b = 1; ( truep( result ) ) && ( b < frame->args ); b++ ) {
+        for ( int b = 1;
-            result = eq( fetch_arg(frame, 0), fetch_arg( frame, b ) ) ? t : nil;
+              ( truep( result ) ) && ( b < frame->payload.stack_frame.args );
+              b++ ) {
+            result =
+                eq( fetch_arg( frame, 0 ), fetch_arg( frame, b ) ) ? t : nil;
         }
     }
 

src/c/ops/repl.h

@@ -0,0 +1,15 @@
+/**
+ *  ops/repl.h
+ *
+ *  The read/eval/print loop.
+ *
+ *  (c) 2026 Simon Brooke <simon@journeyman.cc>
+ *  Licensed under GPL version 2.0, or, at your option, any later version.
+ */
+
+#ifndef __psse_ops_repl_h
+#define __psse_ops_repl_h
+
+// struct pso_pointer repl( struct pso_pointer prompt, struct pso_pointer readtable);
+
+#endif

src/c/ops/stack_ops.h

@@ -0,0 +1,30 @@
+/**
+ *  ops/stack_ops.h
+ *
+ *  Operations on a Lisp stack frame.
+ *
+ *  (c) 2026 Simon Brooke <simon@journeyman.cc>
+ *  Licensed under GPL version 2.0, or, at your option, any later version.
+ */
+
+#ifndef __psse_ops_stack_ops_h
+#define __psse_ops_stack_ops_h
+
+#include "memory/pointer.h"
+#include "memory/pso4.h"
+
+/*
+ * number of arguments stored in a stack frame
+ */
+#define args_in_frame 8
+
+/** 
+ * @brief The maximum depth of stack before we throw an exception.
+ *
+ * `0` is interpeted as `unlimited`.
+ */
+extern uint32_t stack_limit;
+
+struct pso_pointer fetch_arg( struct pso4 *frame, unsigned int index );
+
+#endif

src/c/ops/truth.c

@@ -9,6 +9,12 @@
  *  Licensed under GPL version 2.0, or, at your option, any later version.
  */
 
+#include <stdbool.h>
+
+#include "memory/node.h"
+#include "memory/pointer.h"
+#include "ops/stack_ops.h"
+
 /**
  * @brief true if `p` points to `nil`, else false.
  *
@@ -21,7 +27,7 @@
  * @return false otherwise.
  */
 bool nilp( struct pso_pointer p ) {
-    return (p.page == 0 && p.offset = 0);
+    return ( p.page == 0 && p.offset == 0 );
 }
 
 /**
@@ -47,7 +53,7 @@ bool not( struct pso_pointer p) {
  * @return false otherwise.
  */
 bool truep( struct pso_pointer p ) {
-    return (p.page == 0 && p.offset = 1);
+    return ( p.page == 0 && p.offset == 1 );
 }
 
 /**
@@ -58,10 +64,10 @@ bool truep( struct pso_pointer p) {
  * @param env the evaluation environment.
  * @return `t` if the first argument in this frame is `nil`, else `t`
  */
-pso_pointer lisp_nilp( struct pso4 *frame,
+struct pso_pointer lisp_nilp( struct pso4 *frame,
                        struct pso_pointer frame_pointer,
                        struct pso_pointer env ) {
-    return (nilp(frame->payload.stack_frame.arg[0]) ? t : nil);
+return ( nilp( fetch_arg( frame, 0 )) ? t : nil );
 }
 
 /**
@@ -72,10 +78,10 @@ pso_pointer lisp_nilp( struct pso4 *frame,
  * @param env the evaluation environment.
  * @return `t` if the first argument in this frame is `t`, else `nil`.
  */
-pso_pointer lisp_truep( struct pso4 *frame,
+struct pso_pointer lisp_truep( struct pso4 *frame,
                                  struct pso_pointer frame_pointer,
                                  struct pso_pointer env ) {
-    return (truep(frame->payload.stack_frame.arg[0]) ? t : nil);
+         return ( truep( fetch_arg( frame, 0 ) ) ? t : nil );
 }
 
 /**
@@ -87,8 +93,8 @@ pso_pointer lisp_truep( struct pso4 *frame,
  * @param env the evaluation environment.
  * @return `t` if the first argument in this frame is not `nil`, else `t`.
  */
-pso_pointer lisp_not( struct pso4 *frame,
+struct pso_pointer lisp_not( struct pso4 *frame,
                                struct pso_pointer frame_pointer,
                                struct pso_pointer env ) {
-    return (not(frame->payload.stack_frame.arg[0]) ? t : nil);
+         return ( not( fetch_arg( frame, 0 ) ) ? t : nil );
 }

src/c/ops/truth.h

@@ -11,6 +11,10 @@
 
 #ifndef __psse_ops_truth_h
 #define __psse_ops_truth_h
+#include <stdbool.h>
+
+#include "memory/pointer.h"
+#include "memory/pso4.h"
 
 bool nilp( struct pso_pointer p );
 

src/c/payloads/exception.c

@@ -1,8 +1,16 @@
+/**
+ *  payloads/exception.c
+ *
+ *  An exception; required three pointers, so use object of size class 3.
+ *
+ *  (c) 2026 Simon Brooke <simon@journeyman.cc>
+ *  Licensed under GPL version 2.0, or, at your option, any later version.
+ */
 
 
-#import "memory/pointer.h"
+#include "memory/pointer.h"
-#import "memory/pso.h"
+#include "memory/pso.h"
-#import "payloads/exception.h"
+#include "payloads/exception.h"
 
 /**
  * @param p a pointer to an object.

src/c/payloads/mutex.h

@@ -50,7 +50,8 @@ struct pso_pointer make_mutex();
  * @param forms a list of arbitrary Lisp forms.
  * @return struct pso_pointer the result.
  */
-struct pso_pointer with_lock( struct pso_pointer lock, struct pso_pointer forms);
+struct pso_pointer with_lock( struct pso_pointer lock,
+                              struct pso_pointer forms );
 
 /**
  * @brief as with_lock, q.v. but attempts to obtain a lock and returns an
@@ -64,6 +65,7 @@ struct pso_pointer with_lock( struct pso_pointer lock, struct pso_pointer forms)
  * @param forms a list of arbitrary Lisp forms.
  * @return struct pso_pointer the result.
  */
-struct pso_pointer attempt_with_lock( struct pso_pointer lock, struct pso_pointer forms);
+struct pso_pointer attempt_with_lock( struct pso_pointer lock,
+                                      struct pso_pointer forms );
 
 #endif

src/c/payloads/stack.h

@@ -13,7 +13,7 @@
 #define __psse_payloads_stack_h
 
 #include "memory/pointer.h"
-#include "memory/pso4.h"
+// #include "memory/pso4.h"
 
 #define STACKTAG "STK"
 #define STACKTV  4936787
@@ -23,13 +23,6 @@
  */
 #define args_in_frame 8
 
-/** 
- * @brief The maximum depth of stack before we throw an exception.
- *
- * `0` is interpeted as `unlimited`.
- */
-extern uint32_t stack_limit;
-
 /**
  * A stack frame. 
  */
@@ -48,6 +41,4 @@ struct stack_frame_payload {
     uint32_t depth;
 };
 
-struct pso_pointer fetch_arg( struct pso4 *frame, unsigned int index );
-
 #endif

src/c/psse.c

@@ -14,6 +14,7 @@
 
 #include "psse.h"
 #include "memory/node.h"
+#include "ops/stack_ops.h"
 
 void print_banner(  ) {
     fwprintf( stdout, L"Post-Scarcity Software Environment version %s\n\n",