feat: [+] #66 math functions (#223)

core/src/main/scala/doric/syntax/IntegralType.scala

@@ -0,0 +1,12 @@
+package doric
+package syntax
+
+trait IntegralType[T]
+
+object IntegralType {
+  def apply[T]: IntegralType[T] = new IntegralType[T] {}
+
+  implicit val integralInt: IntegralType[Int] = IntegralType[Int]
+
+  implicit val integralLong: IntegralType[Long] = IntegralType[Long]
+}

core/src/main/scala/doric/syntax/NumWithDecimalsType.scala

@@ -0,0 +1,14 @@
+package doric
+package syntax
+
+trait NumWithDecimalsType[T]
+
+object NumWithDecimalsType {
+  def apply[T]: NumWithDecimalsType[T] = new NumWithDecimalsType[T] {}
+
+  implicit val decimalsDouble: NumWithDecimalsType[Double] =
+    NumWithDecimalsType[Double]
+
+  implicit val decimalsFloat: NumWithDecimalsType[Float] =
+    NumWithDecimalsType[Float]
+}