diff --git a/bin/main.c b/bin/main.c
index 02c98d1..238229c 100644
--- a/bin/main.c
+++ b/bin/main.c
@@ -677,6 +677,7 @@ int main (int argc, char* argv[])
 
 	const char* logopt = HCL_NULL;
 	hcl_oow_t heapsize = DEFAULT_HEAPSIZE;
+	int cflags;
 	int verbose = 0;
 
 #if defined(HCL_BUILD_DEBUG)
@@ -847,6 +848,8 @@ hcl_logufmt (hcl, HCL_LOG_WARN, fmt, ustr, 0x6789);
 	hcl_setoption (hcl, HCL_TRAIT, &trait);
 }
 #endif
+	cflags = 0;
+	if (xtn->reader_istty) cflags = HCL_COMPILE_CLEAR_CODE | HCL_COMPILE_CLEAR_FNBLK;
 
 	while (1)
 	{
@@ -882,17 +885,8 @@ count++;
 			goto oops;
 		}
 
-		if (xtn->reader_istty)
-		{
-			/* clear the byte code buffer */
-			/* TODO: create a proper function for this and call it */
-			hcl->code.bc.len = 0;
-			hcl->code.lit.len = 0;
-		}
-
 		if (verbose) hcl_prbfmt (hcl, "\n"); /* flush the output buffer by hcl_print above */
-
-		n = hcl_compile(hcl, obj);
+		n = hcl_compile(hcl, obj, cflags);
 		hcl_freecnode (hcl, obj); /* not needed any more */
 
 		if (n <= -1)
diff --git a/lib/comp.c b/lib/comp.c
index 21c1425..6fe5f0a 100644
--- a/lib/comp.c
+++ b/lib/comp.c
@@ -3685,13 +3685,18 @@ static HCL_INLINE int emit_throw (hcl_t* hcl)
 
 /* ========================================================================= */
 
-int hcl_compile (hcl_t* hcl, hcl_cnode_t* obj)
+int hcl_compile (hcl_t* hcl, hcl_cnode_t* obj, int flags) 
 {
 	hcl_oow_t saved_bc_len, saved_lit_len;
 	hcl_bitmask_t log_default_type_mask;
 	hcl_fnblk_info_t top_fnblk_saved;
 
 	HCL_ASSERT (hcl, GET_TOP_CFRAME_INDEX(hcl) < 0);
+	if (flags & HCL_COMPILE_CLEAR_CODE)
+	{
+		hcl->code.bc.len = 0;
+		hcl->code.lit.len = 0;
+	}
 
 	saved_bc_len = hcl->code.bc.len;
 	saved_lit_len = hcl->code.lit.len;
@@ -3930,7 +3935,11 @@ int hcl_compile (hcl_t* hcl, hcl_cnode_t* obj)
 
 	HCL_ASSERT (hcl, hcl->c->fnblk.depth == 0); /* ensure the virtual function block be the only one left */
 	hcl->code.ngtmprs = hcl->c->fnblk.info[0].tmprcnt; /* populate the number of global temporary variables */
-	/*pop_fnblk (hcl);  keep the top-level virtual function block by keeping this line commented out */
+	if (flags & HCL_COMPILE_CLEAR_FNBLK)
+	{
+		pop_fnblk (hcl);
+		HCL_ASSERT (hcl, hcl->c->fnblk.depth == -1);
+	}
 
 	hcl ->log.default_type_mask = log_default_type_mask;
 	return 0;
diff --git a/lib/hcl-s.c b/lib/hcl-s.c
index 75ade33..4e987c8 100644
--- a/lib/hcl-s.c
+++ b/lib/hcl-s.c
@@ -1396,7 +1396,7 @@ int hcl_server_proto_handle_request (hcl_server_proto_t* proto)
 			}
 
 			proto->worker->opstate = HCL_SERVER_WORKER_OPSTATE_COMPILE;
-			n = hcl_compile(proto->hcl, obj);
+			n = hcl_compile(proto->hcl, obj, HCL_COMPILE_CLEAR_CODE | HCL_COMPILE_CLEAR_FNBLK);
 			hcl_freecnode (proto->hcl, obj);
 			if (n <= -1)
 			{
diff --git a/lib/hcl.c b/lib/hcl.c
index 22142a9..e457256 100644
--- a/lib/hcl.c
+++ b/lib/hcl.c
@@ -83,9 +83,9 @@ static void fill_bigint_tables (hcl_t* hcl)
 	}
 }
 
-static void* alloc_heap (hcl_t* hcl, hcl_oow_t size)
+static void* alloc_heap (hcl_t* hcl, hcl_oow_t* size)
 {
-	return hcl_allocmem(hcl, size);
+	return hcl_allocmem(hcl, *size);
 }
 
 static void free_heap (hcl_t* hcl, void* ptr)
diff --git a/lib/hcl.h b/lib/hcl.h
index c6fea5e..e3977dc 100644
--- a/lib/hcl.h
+++ b/lib/hcl.h
@@ -1344,6 +1344,16 @@ struct hcl_dbgi_t
 #if defined(HCL_INCLUDE_COMPILER)
 typedef struct hcl_compiler_t hcl_compiler_t;
 typedef struct hcl_cnode_t hcl_cnode_t;
+
+enum hcl_compile_flag_t
+{
+	/* clear byte codes at the beginnign of hcl_compile() */
+	HCL_COMPILE_CLEAR_CODE  = (1 << 0),
+
+	/* clear the top-level function block at the end of hcl_compile() */
+	HCL_COMPILE_CLEAR_FNBLK = (1 << 1)
+};
+typedef enum hcl_compile_flag_t hcl_compile_flag_t;
 #endif
 
 #define HCL_ERRMSG_CAPA (2048)
@@ -2029,10 +2039,13 @@ HCL_EXPORT hcl_ooi_t hcl_proutufmt (
 	...
 );
 
+#if defined(HCL_INCLUDE_COMPILER)
 HCL_EXPORT int hcl_compile (
 	hcl_t*       hcl,
-	hcl_cnode_t* obj
+	hcl_cnode_t* obj,
+	int          flags
 );
+#endif
 
 /**
  * The hcl_decode() function decodes instructions from the position