feat: Add complex numbers

No negation (and therefore no subtraction) since that needs self-reference.

complex/Complex.mjs

@@ -0,0 +1,14 @@
+import typed from 'typed-function'
+
+/* Use a plain object with keys re and im for a complex */
+typed.addType({
+   name: 'Complex',
+   test: z => z && typeof z === 'object' && 're' in z && 'im' in z
+})
+
+typed.addConversion({
+   from: 'number',
+   to: 'Complex',
+   convert: x => ({re: x, im: 0})
+})
+

complex/add.mjs

@@ -0,0 +1,12 @@
+import './Complex.mjs'
+
+export const add = {
+   '...Complex': [[], addends => {
+      const sum = {re: 0, im: 0}
+      addends.forEach(addend => {
+         sum.re += addend.re
+         sum.im += addend.im
+      })
+      return sum
+   }]
+}

complex/all.mjs

@@ -0,0 +1,2 @@
+export {complex} from './complex.mjs'
+export {add} from './add.mjs'

complex/complex.mjs

@@ -0,0 +1,6 @@
+import './Complex.mjs'
+
+export const complex = {
+   'number, number': [[], (x, y) => ({re: x, im: y})],
+   Complex: [[], z => z]
+}