From cc4d77f128ae29540716999177966264d4e3d80a Mon Sep 17 00:00:00 2001
From: Glen Whitney <glen@studioinfinity.org>
Date: Mon, 28 Apr 2025 14:29:08 -0700
Subject: [PATCH] feat: add Vector generic type

---
 src/nanomath.js                    | 10 ++++---
 src/vector/Vector.js               | 43 ++++++++++++++++++++++++++++++
 src/vector/__test__/Vector.spec.js | 35 ++++++++++++++++++++++++
 src/vector/all.js                  |  1 +
 4 files changed, 85 insertions(+), 4 deletions(-)
 create mode 100644 src/vector/Vector.js
 create mode 100644 src/vector/__test__/Vector.spec.js
 create mode 100644 src/vector/all.js

diff --git a/src/nanomath.js b/src/nanomath.js
index ddeeeba..b95aff5 100644
--- a/src/nanomath.js
+++ b/src/nanomath.js
@@ -1,8 +1,9 @@
-import * as booleans from './boolean/all.js'
 import * as coretypes from './coretypes/all.js'
+import * as booleans from './boolean/all.js'
+import * as complex from './complex/all.js'
 import * as generics from './generic/all.js'
 import * as numbers from './number/all.js'
-import * as complex from './complex/all.js'
+import * as vectors from './vector/all.js'
 import {TypeDispatcher} from '#core/TypeDispatcher.js'
 
 // At the moment, since we are not sorting patterns in any way,
@@ -12,9 +13,10 @@ import {TypeDispatcher} from '#core/TypeDispatcher.js'
 // whatever has been merged before.)
 // Hence, in building the math instance, we put generics first because
 // they should only kick in when there are not specific implementations,
-// and complex next becausewe want its conversion (which converts _any_
+// and complex next because we want its conversion (which converts _any_
 // non-complex type to complex, potentially making a poor overload choice)
 // to be tried last.
-const math = new TypeDispatcher(generics, complex, booleans, coretypes, numbers)
+const math = new TypeDispatcher(
+   generics, complex, vectors, booleans, coretypes, numbers)
 
 export default math
diff --git a/src/vector/Vector.js b/src/vector/Vector.js
new file mode 100644
index 0000000..0f82e4f
--- /dev/null
+++ b/src/vector/Vector.js
@@ -0,0 +1,43 @@
+import {NotAType, Type} from '#core/Type.js'
+
+const isVector = v => Array.isArray(v)
+
+export const Vector = new Type(isVector, {
+   specialize(CompType) {
+      const compTest = CompType.test
+      const specTest = v => isVector(v) && v.every(compTest)
+      const typeName = `Vector(${CompType})`
+      if (CompType.concrete) {
+         const typeOptions = {typeName}
+         if ('zero' in CompType) typeOptions.zero = [CompType.zero]
+         const vectorCompType = new Type(specTest, typeOptions)
+         vectorCompType.Component = CompType
+         vectorCompType.vector = true
+         return vectorCompType
+      }
+      // Wrapping a generic type in Vector
+      return new Type(specTest, {
+         typeName,
+         specialize: (...args) => this.specialize(CompType.specialize(...args)),
+         specializesTo: VT => this.specializesTo(VT)
+            && CompType.specializesTo(VT.Component),
+         refine: (v, typer) => {
+            const eltTypes = v.map(elt => CompType.refine(elt, typer))
+            const newCompType = eltTypes[0]
+            if (eltTypes.some(T => T !== newCompType)) {
+               throw new TypeError(
+                  `can't refine ${typeName} to ${v}; `
+                  + `not all entries have type ${newCompType}`)
+            }
+            return this.specialize(newCompType)
+         }
+      })
+   },
+   specializesTo: VT => VT.vector,
+   refine(v, typer) {
+      const eltTypes = v.map(elt => typer(elt))
+      let compType = eltTypes[0]
+      if (eltTypes.some(T => T !== compType)) compType = NotAType
+      return this.specialize(compType)
+   }
+})
diff --git a/src/vector/__test__/Vector.spec.js b/src/vector/__test__/Vector.spec.js
new file mode 100644
index 0000000..5233bb5
--- /dev/null
+++ b/src/vector/__test__/Vector.spec.js
@@ -0,0 +1,35 @@
+import assert from 'assert'
+import {Vector} from '../Vector.js'
+import {NotAType} from '#core/Type.js'
+import math from '#nanomath'
+
+describe('Vector Type', () => {
+   it('correctly recognizes vectors', () => {
+      assert(Vector.test([3, 4]))
+      assert(!Vector.test({re: 3, im: 4}))
+   })
+   it('can fully type vectors', () => {
+      const {BooleanT, Complex, NumberT} = math.types
+      const typ = math.typeOf
+      const cplx = math.complex
+      assert.strictEqual(typ([3, 4]), Vector(NumberT))
+      assert.strictEqual(typ([true, false]), Vector(BooleanT))
+      assert.strictEqual(typ([3, false]), Vector(NotAType))
+      assert.strictEqual(typ([cplx(3, 4), cplx(5)]), Vector(Complex(NumberT)))
+      assert.strictEqual(typ([[3, 4], [5]]), Vector(Vector(NumberT)))
+   })
+   it('can refine when nested', () => {
+      const {Complex, NumberT} = math.types
+      const cplx = math.complex
+      const VecComplex = Vector(Complex)
+      const vcEx = [cplx(3, 4), cplx(5)]
+      assert(VecComplex.test(vcEx))
+      const vcType = VecComplex.refine(vcEx, math.typeOf)
+      assert.strictEqual(vcType, Vector(Complex(NumberT)))
+      const CplxVec = Complex(Vector)
+      const cvEx = cplx([3,4], [5, 0])
+      assert(CplxVec.test(cvEx))
+      const cvType = CplxVec.refine(cvEx, math.typeOf)
+      assert.strictEqual(cvType, Complex(Vector(NumberT)))
+   })
+})
diff --git a/src/vector/all.js b/src/vector/all.js
new file mode 100644
index 0000000..b5fe798
--- /dev/null
+++ b/src/vector/all.js
@@ -0,0 +1 @@
+export * as typeDefinition from './Vector.js'