diff --git a/ase/cmd/awk/awk.c b/ase/cmd/awk/awk.c
index 27be055d..3f57d8fa 100644
--- a/ase/cmd/awk/awk.c
+++ b/ase/cmd/awk/awk.c
@@ -1,5 +1,5 @@
 /*
- * $Id: awk.c 321 2008-08-10 08:27:21Z baconevi $
+ * $Id: awk.c 323 2008-08-11 10:52:25Z baconevi $
  */
 
 #include <ase/awk/awk.h>
@@ -1056,9 +1056,10 @@ static void handle_args (argc, argv)
 }
 #endif
 
-static int dump_sf (ase_sll_t* sll, ase_sll_node_t* n, void* arg)
+static ase_sll_walk_t dump_sf (ase_sll_t* sll, ase_sll_node_t* n, void* arg)
 {
 	ase_printf (ASE_T("%s\n"), n->data.ptr);
+	return ASE_SLL_WALK_FORWARD;
 }
 
 static int handle_args (int argc, ase_char_t* argv[], ase_sll_t* sf)
@@ -1171,6 +1172,7 @@ wprintf (L"PREPEND %S\n", opt.arg);
 
 ase_printf (ASE_T("[%d]\n"), (int)ase_sll_getsize(sf));
 ase_sll_walk (sf, dump_sf, ASE_NULL);
+
 #if 0
 	if (srcio->input_file == ASE_NULL)
 	{
@@ -1261,6 +1263,11 @@ static ase_awk_t* open_awk (void)
 	return awk;
 }
 
+static ase_sll_walk_t dump (ase_sll_t* sll, ase_sll_node_t* node, void* arg)
+{
+	ase_printf (ASE_T("[%d]\n"), *(int*)node->data.ptr);
+	return ASE_SLL_WALK_FORWARD;
+}
 static int awk_main (int argc, ase_char_t* argv[])
 {
 	ase_awk_t* awk;
@@ -1287,7 +1294,32 @@ static int awk_main (int argc, ase_char_t* argv[])
 		out_of_memory ();
 		return -1;
 	}	
+{
 // TODO: destroy sf....
+int i;
+
+ase_sll_setcopier (sf, ASE_SLL_COPIER_INLINE);
+for (i = 0; i < 20; i++)
+{
+	/*
+	if (ASE_SLL_SIZE(sf) > 5)
+		ase_sll_insert (sf, sf->head->next->next, &i, sizeof(i));
+	else
+	ase_sll_insert (sf, ASE_SLL_HEAD(sf), &i, sizeof(i));
+	*/
+	ase_sll_insert (sf, ASE_NULL, &i, sizeof(i));
+}
+
+ase_sll_delete (sf, ASE_SLL_TAIL(sf));
+ase_sll_delete (sf, ASE_SLL_TAIL(sf));
+ase_sll_delete (sf, ASE_SLL_HEAD(sf));
+ase_printf (ASE_T("size = %d\n"), ASE_SLL_SIZE(sf));
+ase_sll_walk (sf, dump, ASE_NULL);
+ase_sll_clear (sf);
+ase_printf (ASE_T("size = %d\n"), ASE_SLL_SIZE(sf));
+ase_sll_close (sf);
+return 0;
+}
 
 	i = handle_args (argc, argv, sf);
 	if (i == -1)
diff --git a/ase/include/ase/cmn/sll.h b/ase/include/ase/cmn/sll.h
index 8d979f38..c1179412 100644
--- a/ase/include/ase/cmn/sll.h
+++ b/ase/include/ase/cmn/sll.h
@@ -17,6 +17,28 @@ typedef struct ase_sll_t ase_sll_t;
 typedef struct ase_sll_node_t ase_sll_node_t;
 typedef enum ase_sll_walk_t ase_sll_walk_t;
 
+/* data copier */
+typedef void* (*ase_sll_copier_t) (ase_sll_t* sll, void* data, ase_size_t len);
+
+/* data freeer */
+typedef void (*ase_sll_freeer_t) (ase_sll_t* sll, void* data, ase_size_t len);
+
+/* node visitor */
+typedef ase_sll_walk_t (*ase_sll_walker_t) (
+	ase_sll_t* sll, ase_sll_node_t* node, void* arg);
+
+struct ase_sll_t
+{
+	ase_mmgr_t* mmgr;
+
+	ase_sll_copier_t copier;
+	ase_sll_freeer_t freeer;
+
+	ase_size_t size;
+	ase_sll_node_t* head;
+	ase_sll_node_t* tail;
+};
+
 struct ase_sll_node_t
 {
 	struct
@@ -28,9 +50,6 @@ struct ase_sll_node_t
 	ase_sll_node_t* next;   /* pointer to the next node */
 };
 
-typedef void* (*ase_sll_copier_t) (ase_sll_t* sll, void* data, ase_size_t len);
-typedef void (*ase_sll_freeer_t) (ase_sll_t* sll, void* data, ase_size_t len);
-typedef ase_sll_walk_t (*ase_sll_walker_t) (ase_sll_t* sll, ase_sll_node_t* node, void* arg);
 
 enum ase_sll_walk_t
 {
@@ -40,6 +59,10 @@ enum ase_sll_walk_t
 
 #define ASE_SLL_COPIER_INLINE ase_sll_copyinline
 
+#define ASE_SLL_HEAD(sll) ((sll)->head)
+#define ASE_SLL_TAIL(sll) ((sll)->tail)
+#define ASE_SLL_SIZE(sll) ((sll)->size)
+
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/ase/lib/cmn/sll.c b/ase/lib/cmn/sll.c
index fd032a70..4edeced1 100644
--- a/ase/lib/cmn/sll.c
+++ b/ase/lib/cmn/sll.c
@@ -7,18 +7,6 @@
 #include <ase/cmn/sll.h>
 #include "mem.h"
 
-struct ase_sll_t
-{
-	ase_mmgr_t* mmgr;
-
-	ase_sll_copier_t copier;
-	ase_sll_freeer_t freeer;
-
-	ase_size_t size;
-	ase_sll_node_t* head;
-	ase_sll_node_t* tail;
-};
-
 void* ase_sll_copyinline (ase_sll_t* sll, void* dptr, ase_size_t dlen)
 {
 	/* this is a dummy copier */
@@ -52,20 +40,8 @@ void ase_sll_close (ase_sll_t* sll)
 
 void ase_sll_clear (ase_sll_t* sll)
 {
-	while (sll->head != ASE_NULL)
-	{
-		ase_sll_node_t* h = sll->head;
-		sll->head = h->next;
-
-		if (sll->freeer != ASE_NULL)
-		{
-			sll->freeer (sll, h->data.ptr, h->data.len);
-		}
-	
-		ASE_FREE (sll->mmgr, h);
-	}	
-
-	sll->tail = ASE_NULL;
+	while (sll->head != ASE_NULL) ase_sll_delete (sll, sll->head);
+	ASE_ASSERT (sll->tail == ASE_NULL);
 }
 
 void* ase_sll_getextension (ase_sll_t* sll)
@@ -93,7 +69,7 @@ ase_sll_copier_t ase_sll_getcopier (ase_sll_t* sll)
 	return sll->copier;
 }
 
-void ass_sll_setcopier (ase_sll_t* sll, ase_sll_copier_t copier)
+void ase_sll_setcopier (ase_sll_t* sll, ase_sll_copier_t copier)
 {
 	sll->copier = copier;
 }
@@ -187,22 +163,38 @@ ase_sll_node_t* ase_sll_pushtail (ase_sll_t* sll, void* data, ase_size_t size)
 
 void ase_sll_delete (ase_sll_t* sll, ase_sll_node_t* pos)
 {
-	ASE_ASSERT (pos != ASE_NULL);
+	if (pos == ASE_NULL) return; /* not a valid node */
 
 	if (pos == sll->head)
 	{
+		/* it is simple to delete the head node */
 		sll->head = pos->next;
 		if (sll->head == ASE_NULL) sll->tail = ASE_NULL;
 	}
 	else 
 	{
-		/* take note of performance penalty */
+		/* but deletion of other nodes has significant performance
+		 * penalty as it has look for the predecessor of the 
+		 * target node */
 		ase_sll_node_t* n2 = sll->head;
 		while (n2->next != pos) n2 = n2->next;
+
 		n2->next = pos->next;
+
+		/* update the tail node if necessary */
 		if (pos == sll->tail) sll->tail = n2;
 	}
 
+	if (sll->freeer != ASE_NULL)
+	{
+		/* free the actual data */
+		sll->freeer (sll, pos->data.ptr, pos->data.len);
+	}
+
+	/* free the node */
+	ASE_FREE (sll->mmgr, pos);
+
+	/* decrement the number of elements */
 	sll->size--;
 }