add missing finite? function

src/number.c

@@ -53,6 +53,21 @@ pic_number_inexact_p(pic_state *pic)
   return pic_bool_value(pic_float_p(v));
 }
 
+static pic_value
+pic_number_finite_p(pic_state *pic)
+{
+  pic_value v;
+
+  pic_get_args(pic, "o", &v);
+
+  if (pic_int_p(v))
+    return pic_true_value();
+  if (pic_float_p(v) && ! (isinf(pic_float(v)) || isnan(pic_float(v))))
+    return pic_true_value();
+  else
+    return pic_false_value();
+}
+
 static pic_value
 pic_number_infinite_p(pic_state *pic)
 {