Whoops! Had the wrong debug tag on debug calls in equal.c

src/memory/consspaceobject.c

@@ -150,7 +150,7 @@ struct cons_pointer c_car( struct cons_pointer arg ) {
 
 /**
  * Implementation of cdr in C. If arg is not a sequence, or the current user is
- * not authorised to read it,does not error but returns nil.
+ * not authorised to read it, does not error but returns nil.
  */
 struct cons_pointer c_cdr( struct cons_pointer arg ) {
     struct cons_pointer result = NIL;

src/ops/equal.c

@@ -9,6 +9,7 @@
 
 #include <math.h>
 #include <stdbool.h>
+#include <string.h>
 
 #include "arith/integer.h"
 #include "arith/peano.h"
@@ -363,22 +364,38 @@ bool equal( struct cons_pointer a, struct cons_pointer b ) {
                 /* TODO: it is not OK to do this on the stack since list-like 
                  * structures can be of indefinite extent. It *must* be done by 
                  * iteration (and even that is problematic) */
+                if (cell_a->payload.string.hash == cell_b->payload.string.hash) {
+                    wchar_t a_buff[ STRING_SHIPYARD_SIZE], b_buff[ STRING_SHIPYARD_SIZE];
+                    uint32_t tag = cell_a->tag.value;
+                    int i = 0;
+
+                    memset(a_buff,0,sizeof(a_buff));
+                    memset(b_buff,0,sizeof(b_buff));
+
+                    for (; (i < (STRING_SHIPYARD_SIZE - 1)) && !nilp( a) && !nilp( b); i++) {
+                        a_buff[i] = cell_a->payload.string.character;
+                        a = c_cdr(a);
+                        cell_a = &pointer2cell( a );
+
+                        b_buff[i] = cell_b->payload.string.character;
+                        b = c_cdr( b);
+                        cell_b = &pointer2cell( b); 
+                    }
+
 #ifdef DEBUG
-                 debug_print( L"Comparing '", DEBUG_ARITH);
-                 debug_print_object( a, DEBUG_ARITH);
-                 debug_print( L"' to '", DEBUG_ARITH);
-                 debug_print_object( b, DEBUG_ARITH);
+                    debug_print( L"Comparing '", DEBUG_ARITH);
+                    debug_print( a_buff, DEBUG_ARITH);
+                    debug_print( L"' to '", DEBUG_ARITH);
+                    debug_print( b_buff, DEBUG_ARITH);
+                    debug_print( L"'\n", DEBUG_ARITH);
 #endif
-                result =
-                    cell_a->payload.string.hash == cell_b->payload.string.hash
-                    && cell_a->payload.string.character ==
-                    cell_b->payload.string.character
-                    &&
-                    ( equal
-                      ( cell_a->payload.string.cdr,
-                        cell_b->payload.string.cdr )
-                      || ( end_of_string( cell_a->payload.string.cdr )
-                           && end_of_string( cell_b->payload.string.cdr ) ) );
+
+                    /* OK, now we have wchar string buffers loaded from the objects. We 
+                     * may not have exhausted either string, so the buffers being equal
+                     * isn't sufficient. So we recurse at least once. */
+
+                    result = (wcsncmp( a_buff, b_buff, i) == 0) && equal( c_cdr(a), c_cdr(b));
+                }
                 break;
             case VECTORPOINTTV:
                 if ( cell_b->tag.value == VECTORPOINTTV) {

src/ops/equal.h

@@ -15,6 +15,12 @@
 #ifndef __equal_h
 #define __equal_h
 
+/** 
+ * size of buffer for assembling strings. Likely to be useful to
+ * read, too.
+ */
+#define STRING_SHIPYARD_SIZE 1024
+
 /**
  * Shallow, and thus cheap, equality: true if these two objects are 
  * the same object, else false.

src/ops/lispops.c

@@ -1639,7 +1639,6 @@ struct cons_pointer lisp_let( struct stack_frame *frame,
 
             bindings =
                 make_cons( make_cons( symbol, val ), bindings );
-
         } else {
             result =
                 throw_exception( c_string_to_lisp_string
@@ -1649,6 +1648,8 @@ struct cons_pointer lisp_let( struct stack_frame *frame,
         }
     }
 
+    debug_print( L"\nlet: bindings complete.\n", DEBUG_BIND);
+
     /* i.e., no exception yet */
     for ( int form = 1; !exceptionp( result ) && form < frame->args; form++ ) {
         result =
@@ -1656,10 +1657,11 @@ struct cons_pointer lisp_let( struct stack_frame *frame,
                        bindings );
     }
 
-    // release the local bindings as they go out of scope!
-    for (struct cons_pointer cursor = bindings; !eq( cursor, env); cursor = c_cdr(cursor)) {
-        dec_ref( cursor);
-    }
+    /* release the local bindings as they go out of scope! **BUT** 
+     * bindings were consed onto the front of env, so caution... */
+    // for (struct cons_pointer cursor = bindings; !eq( cursor, env); cursor = c_cdr(cursor)) {
+    //     dec_ref( cursor);
+    // }
 
     return result;
 

unit-tests/let.sh

@@ -2,28 +2,28 @@
 
 result=0
 
-# echo -n "$0: let with two bindings, one form in body..."
-# expected='11'
-# actual=`echo "(let ((a . 5)(b . 6)) (+ a b))" | target/psse 2>/dev/null | tail -1`
+echo -n "$0: let with two bindings, one form in body..."
+expected='11'
+actual=`echo "(let ((a . 5)(b . 6)) (+ a b))" | target/psse 2>/dev/null | tail -1`
 
-# if [ "${expected}" = "${actual}" ]
-# then
-#     echo "OK"
-# else
-#     echo "Fail: expected '$expected', got '$actual'"
-#     result=`echo "${result} + 1" | bc`
-# fi
+if [ "${expected}" = "${actual}" ]
+then
+    echo "OK"
+else
+    echo "Fail: expected '$expected', got '$actual'"
+    result=`echo "${result} + 1" | bc`
+fi
 
-# echo -n "$0: let with two bindings, two forms in body..."
-# expected='1'
-# actual=`echo "(let ((a . 5)(b . 6)) (+ a b) (- b a))" | target/psse 2>/dev/null | tail -1`
+echo -n "$0: let with two bindings, two forms in body..."
+expected='1'
+actual=`echo "(let ((a . 5)(b . 6)) (+ a b) (- b a))" | target/psse 2>/dev/null | tail -1`
 
-# if [ "${expected}" = "${actual}" ]
-# then
-#     echo "OK"
-# else
-#     echo "Fail: expected '$expected', got '$actual'"
-#     result=`echo "${result} + 1" | bc`
-# fi
+if [ "${expected}" = "${actual}" ]
+then
+    echo "OK"
+else
+    echo "Fail: expected '$expected', got '$actual'"
+    result=`echo "${result} + 1" | bc`
+fi
 
 exit ${result}