add String type + use String to make nominal types unique (worse, but more pleasant when debugging)

lib/point.js

@@ -1,17 +1,21 @@
 import { Function, Type } from "../metacircular.js";
 import { Double } from "../primitives/symbols.js";
+import { String } from "../structures/list_types/string.js";
 import { nominalType, NominalType } from "../structures/nominal_type.js";
+import { makeProductType } from "../structures/product.js";
 import { fnType, prodType, typedFnType } from "../type_registry.js";
 
 const PointCartesian2D = nominalType(
   // just a unique number, to make sure that our type is only equal to itself
-  BigInt("0xBBAAD62B10EE21993BA690A732DA2A6875CE4B6F5E7139D5AEC9FD887F9D24A8"))
-  (prodType(Double, Double));
+  "PointCartesian2D")
+  // BigInt("0xBBAAD62B10EE21993BA690A732DA2A6875CE4B6F5E7139D5AEC9FD887F9D24A8"))
+  (prodType(String, Double));
 
 const PointPolar2D = nominalType(
   // just a unique number, to make sure that our type is only equal to itself
-  BigInt("0x31CDAB4B3D84C4EB27D3C111FD7580E533268B72E05BD694F8B262913E018B72"))
-  (prodType(Double, Double));
+  "PointPolar2D")
+  // BigInt("0x31CDAB4B3D84C4EB27D3C111FD7580E533268B72E05BD694F8B262913E018B72"))
+  (prodType(String, Double));
 
 export const cart2polar = ({left: x, right: y}) => {
   const r = Math.sqrt(x*x + y*y);
@@ -37,10 +41,15 @@ export const scale = dr => ({left: r, right: θ}) => {
   return {left: r+dr, right: θ};
 }
 
+const examplePoint = {left: 1, right: 2};
+
 export const ModulePoint = {l:[
   {i: -1                 , t: Double},
   {i: 2                  , t: Double},
-  {i: {left: 1, right: 2}, t: PointCartesian2D},
+  {i: examplePoint       , t: PointCartesian2D},
+  {i: examplePoint       , t: prodType(Double, Double)},
+
+  ...makeProductType(Double, Double).l,
 
   {i: PointCartesian2D   , t: NominalType},
   {i: PointPolar2D       , t: NominalType},