branching and very basic merging of slots

typeclasses/show.js

@@ -0,0 +1,9 @@
+import { cart2Str, NPoint2DCartesian, NPoint2DPolar, polar2Str } from "../lib/point.js";
+import { Type } from "../primitives/types.js";
+import { prettyT } from "../structures/types.js";
+
+export const ShowInstances = new Map([
+  [Type             , {show: prettyT}],
+  [NPoint2DCartesian, {show: cart2Str}],
+  [NPoint2DPolar    , {show: polar2Str}],
+]);