diff --git a/lib/comp.c b/lib/comp.c
index 610decd..825ed23 100644
--- a/lib/comp.c
+++ b/lib/comp.c
@@ -554,7 +554,7 @@ static HCL_INLINE int _insert_cframe (hcl_t* hcl, hcl_ooi_t index, int opcode, h
 
 		newcapa = HCL_ALIGN (hcl->c->cfs.top + 256, 256); /* TODO: adjust this capacity */
 		tmp = (hcl_cframe_t*)hcl_reallocmem (hcl, hcl->c->cfs.ptr, newcapa * HCL_SIZEOF(hcl_cframe_t));
-		if (!tmp) 
+		if (HCL_UNLIKELY(!tmp)) 
 		{
 			hcl->c->cfs.top--;
 			return -1;
@@ -584,7 +584,7 @@ static int insert_cframe (hcl_t* hcl, hcl_ooi_t index, int opcode, hcl_oop_t ope
 		return -1;
 	}
 
-	return _insert_cframe (hcl, index, opcode, operand);
+	return _insert_cframe(hcl, index, opcode, operand);
 }
 
 static int push_cframe (hcl_t* hcl, int opcode, hcl_oop_t operand)
@@ -595,7 +595,7 @@ static int push_cframe (hcl_t* hcl, int opcode, hcl_oop_t operand)
 		return -1;
 	}
 
-	return _insert_cframe (hcl, hcl->c->cfs.top + 1, opcode, operand);
+	return _insert_cframe(hcl, hcl->c->cfs.top + 1, opcode, operand);
 }
 
 static HCL_INLINE void pop_cframe (hcl_t* hcl)
@@ -643,7 +643,7 @@ static int push_subcframe (hcl_t* hcl, int opcode, hcl_oop_t operand)
 	cf->opcode = opcode;
 	cf->operand = operand;
 
-	return push_cframe (hcl, tmp.opcode, tmp.operand);
+	return push_cframe(hcl, tmp.opcode, tmp.operand);
 }
 
 static HCL_INLINE hcl_cframe_t* find_cframe_from_top (hcl_t* hcl, int opcode)
@@ -1779,7 +1779,7 @@ static int compile_object (hcl_t* hcl)
 	return 0;
 
 literal:
-	if (emit_push_literal (hcl, cf->operand) <= -1) return -1;
+	if (emit_push_literal(hcl, cf->operand) <= -1) return -1;
 
 done:
 	POP_CFRAME (hcl);
diff --git a/lib/hcl-prv.h b/lib/hcl-prv.h
index 371ee55..6510ec5 100644
--- a/lib/hcl-prv.h
+++ b/lib/hcl-prv.h
@@ -181,6 +181,60 @@ struct hcl_iolink_t
 	hcl_iolink_t* link;
 };
 
+typedef enum hcl_concode_t hcl_concode_t;
+enum hcl_cnode_type_t
+{
+	HCL_CNODE_CHARLIT,
+	HCL_CNODE_STRLIT,
+	HCL_CNODE_NUMLIT,
+	HCL_CNODE_RADNUMLIT,
+	HCL_CNODE_FPDECLIT,
+	HCL_CNODE_SMPTRLIT,
+	HCL_CNODE_ERRORLIT,
+	HCL_CNODE_NIL,
+	HCL_CNODE_TRUE,
+	HCL_CNODE_FALSE,
+
+	HCL_CNODE_AND = 1,
+	HCL_CNODE_BREAK,
+	HCL_CNODE_DEFUN,
+	HCL_CNODE_DO,
+	HCL_CNODE_ELIF,
+	HCL_CNODE_ELSE,
+	HCL_CNODE_IF,
+	HCL_CNODE_LAMBDA,
+	HCL_CNODE_OR,
+	HCL_CNODE_RETURN,
+	HCL_CNODE_RETURN_FROM_HOME,
+	HCL_CNODE_SET,
+	HCL_CNODE_UNTIL,
+	HCL_CNODE_WHILE,
+
+	HCL_CNODE_XLIST = 0,  /* () - executable list */
+	HCL_CNODE_ARRAY,      /* [] */
+	HCL_CNODE_BYTEARRAY,  /* #[] */
+	HCL_CNODE_DIC,        /* {} */
+	HCL_CNODE_QLIST       /* #() - data list */
+};
+typedef enum hcl_cnode_type_t hcl_cnode_type_t;
+
+/* NOTE: hcl_cnode_t used by the built-in compiler is not an OOP object */
+struct hcl_cnode_t
+{
+	hcl_cnode_type_t type;
+	hcl_ioloc_t loc;
+
+	union
+	{
+		struct
+		{
+			hcl_ooch_t* ptr;
+			hcl_oow_t len;
+		} strlit;
+	} u;
+};
+typedef struct hcl_cnode_t hcl_cnode_t;
+
 /* NOTE: hcl_cframe_t used by the built-in compiler is not an OOP object */
 struct hcl_cframe_t
 {
@@ -221,7 +275,6 @@ struct hcl_cframe_t
 		} lambda;
 	} u;
 };
-
 typedef struct hcl_cframe_t hcl_cframe_t;
 
 struct hcl_blk_info_t
diff --git a/lib/hcl.h b/lib/hcl.h
index 043d590..35d34b0 100644
--- a/lib/hcl.h
+++ b/lib/hcl.h
@@ -1675,7 +1675,6 @@ enum hcl_brand_t
 	HCL_BRAND_DIC,
 	HCL_BRAND_FPDEC, /* fixed-point decimal */
 
-	HCL_BRAND_CFRAME,/* compiler frame */
 	HCL_BRAND_PRIM,
 
 	HCL_BRAND_FUNCTION,
@@ -1691,6 +1690,7 @@ typedef enum hcl_brand_t hcl_brand_t;
 enum hcl_syncode_t
 {
 	/* SYNCODE 0 means it's not a syncode object. so it begins with 1 */
+	/* these enumerators can be set in the SYNCODE flags for a symbol */
 	HCL_SYNCODE_AND = 1,
 	HCL_SYNCODE_BREAK,
 	HCL_SYNCODE_DEFUN,
@@ -1710,7 +1710,7 @@ typedef enum hcl_syncode_t hcl_syncode_t;
 
 enum hcl_concode_t
 {
-	/* these can be set in the SYNCODE flags for cons cells */
+	/* these can be set in the SYNCODE flags for a cons cell */
 	HCL_CONCODE_XLIST = 0,  /* () - executable list */
 	HCL_CONCODE_ARRAY,      /* [] */
 	HCL_CONCODE_BYTEARRAY,  /* #[] */
diff --git a/lib/print.c b/lib/print.c
index 2959aef..b79f426 100644
--- a/lib/print.c
+++ b/lib/print.c
@@ -84,7 +84,6 @@ enum
 	WORD_FALSE,
 
 	WORD_SET,
-	WORD_CFRAME,
 	WORD_PRIM,
 
 	WORD_FUNCTION,
@@ -655,10 +654,6 @@ next:
 			break;
 		}
 
-		case HCL_BRAND_CFRAME:
-			word_index = WORD_CFRAME;
-			goto print_word;
-
 		case HCL_BRAND_PRIM:
 			word_index = WORD_PRIM;
 			goto print_word;