diff --git a/lib/bigint.c b/lib/bigint.c
index 8ee9d40..75ef5d0 100644
--- a/lib/bigint.c
+++ b/lib/bigint.c
@@ -4031,6 +4031,32 @@ oops:
 	return HCL_NULL;
 }
 
+
+hcl_oop_t hcl_absint (hcl_t* hcl, hcl_oop_t x)
+{
+	if (HCL_OOP_IS_SMOOI(x))
+	{
+		hcl_ooi_t v;
+		v = HCL_OOP_TO_SMOOI(x);
+		if (v < 0) 
+		{
+			v = -v;
+			x = HCL_SMOOI_TO_OOP(v);
+		}
+	}
+	else if (HCL_IS_NBIGINT(hcl, x))
+	{
+		x = _clone_bigint(hcl, x, HCL_OBJ_GET_SIZE(x), HCL_BRAND_PBIGINT);
+	}
+	else if (!HCL_IS_PBIGINT(hcl, x))
+	{
+		hcl_seterrbfmt (hcl, HCL_EINVAL, "parameter not integer - %O", x);
+		return HCL_NULL;
+	}
+
+	return x;
+}
+
 hcl_oop_t hcl_inttostr (hcl_t* hcl, hcl_oop_t num, int radix, int ngc)
 {
 	hcl_ooi_t v = 0;
diff --git a/lib/hcl-prv.h b/lib/hcl-prv.h
index 91021c5..124aa6f 100644
--- a/lib/hcl-prv.h
+++ b/lib/hcl-prv.h
@@ -946,6 +946,11 @@ hcl_oop_t hcl_sqrtint (
 	hcl_oop_t x
 );
 
+hcl_oop_t hcl_absint (
+	hcl_t*    hcl,
+	hcl_oop_t x
+);
+
 hcl_oop_t hcl_strtoint (
 	hcl_t*            hcl,
 	const hcl_ooch_t* str,
@@ -1050,13 +1055,9 @@ hcl_oop_t hcl_sqrtnum (
 	hcl_oop_t    x
 );
 
-
-/* ========================================================================= */
-/* comp.c                                                                    */
-/* ========================================================================= */
-HCL_EXPORT int hcl_compile (
-	hcl_t*         hcl,
-	hcl_oop_t      expr
+hcl_oop_t hcl_absnum (
+	hcl_t*       hcl,
+	hcl_oop_t    x
 );
 
 /* ========================================================================= */
diff --git a/lib/number.c b/lib/number.c
index df2da0f..1753f8e 100644
--- a/lib/number.c
+++ b/lib/number.c
@@ -374,3 +374,24 @@ hcl_oop_t hcl_sqrtnum (hcl_t* hcl, hcl_oop_t x)
 		return hcl_makefpdec(hcl, v, scale);
 	}
 }
+
+hcl_oop_t hcl_absnum (hcl_t* hcl, hcl_oop_t x)
+{
+	if (!HCL_IS_FPDEC(hcl, x))
+	{
+		return hcl_absint(hcl, x);
+	}
+	else
+	{
+		hcl_oop_t v;
+		hcl_ooi_t scale;
+
+		scale = HCL_OOP_TO_SMOOI(((hcl_oop_fpdec_t)x)->scale);
+		v = ((hcl_oop_fpdec_t)x)->value;
+		
+		v = hcl_absint(hcl, v);
+		if (!v) return HCL_NULL;
+		
+		return hcl_makefpdec(hcl, v, scale);
+	}
+}
diff --git a/lib/prim.c b/lib/prim.c
index 661353d..3c80a61 100644
--- a/lib/prim.c
+++ b/lib/prim.c
@@ -502,7 +502,17 @@ static hcl_pfrc_t pf_number_rem (hcl_t* hcl, hcl_mod_t* mod, hcl_ooi_t nargs)
 static hcl_pfrc_t pf_number_sqrt (hcl_t* hcl, hcl_mod_t* mod, hcl_ooi_t nargs)
 {
 	hcl_oop_t ret;
-	ret = hcl_sqrtnum(hcl, HCL_STACK_GETARG(hcl, nargs, 0)); /*TODO: change to hcl_sqrtnum()*/
+	ret = hcl_sqrtnum(hcl, HCL_STACK_GETARG(hcl, nargs, 0));
+	if (!ret) return HCL_PF_FAILURE;
+
+	HCL_STACK_SETRET (hcl, nargs, ret);
+	return HCL_PF_SUCCESS;
+}
+
+static hcl_pfrc_t pf_number_abs (hcl_t* hcl, hcl_mod_t* mod, hcl_ooi_t nargs)
+{
+	hcl_oop_t ret;
+	ret = hcl_absnum(hcl, HCL_STACK_GETARG(hcl, nargs, 0)); 
 	if (!ret) return HCL_PF_FAILURE;
 
 	HCL_STACK_SETRET (hcl, nargs, ret);
@@ -640,6 +650,12 @@ static pf_t builtin_prims[] =
 	{ 2, 2,                       pf_nql,             4,  { 'n','q','l','?' } },
 	{ 2, 2,                       pf_nqk,             4,  { 'n','q','k','?' } },
 
+/*
+	{ 1, 1,                       pf_is_null,         4,  { 'n','u','l','l','?' } },
+	{ 1, 1,                       pf_is_integer,      8,  { 'i','n','t','e','g','e','r','?' } },
+	{ 1, 1,                       pf_is_string,       7,  { 's','t','r','i','n','g','?' } },
+*/
+
 	{ 1, HCL_TYPE_MAX(hcl_oow_t), pf_number_add,      1,  { '+' } },
 	{ 1, HCL_TYPE_MAX(hcl_oow_t), pf_number_sub,      1,  { '-' } },
 	{ 1, HCL_TYPE_MAX(hcl_oow_t), pf_number_mul,      1,  { '*' } },
@@ -648,6 +664,7 @@ static pf_t builtin_prims[] =
 	{ 1, HCL_TYPE_MAX(hcl_oow_t), pf_number_quo,      3,  { 'q','u','o' } },
 	{ 2, HCL_TYPE_MAX(hcl_oow_t), pf_number_rem,      3,  { 'm','o','d' } },
 	{ 1, 1,                       pf_number_sqrt,     4,  { 's','q','r','t' } },
+	{ 1, 1,                       pf_number_abs,      3,  { 'a','b','s' } },
 
 	{ 2, 2,                       pf_number_gt,       1,  { '>' } },
 	{ 2, 2,                       pf_number_ge,       2,  { '>','=' } },