feat: Implement Vector type (#28)

The Vector type is simply a generic type for built-in JavaScript Arrays. The parameter type is the type of all of the entries of the Array. The Vector type also supports inhomogeneous arrays by using the special type `Unknown` as the argument type, but note that when computing with inhomogeneous arrays, method dispatch must be performed separately for every entry in a calculation, making all operations considerably slower than on homogeneous Vector instances.

Note also that arithmetic operations on nested Vectors, e.g. `Vector(Vector(NumberT))` are defined so as to interpret such entities as ordinary matrices, represented in row-major format (i.e., the component `Vector(NumberT)` items of such an entity are the _rows_ of the matrix.

Reviewed-on: #28
Co-authored-by: Glen Whitney <glen@studioinfinity.org>
Co-committed-by: Glen Whitney <glen@studioinfinity.org>

src/generic/arithmetic.js

@@ -1,15 +1,20 @@
 import {ReturnsAs} from './helpers.js'
 
-import {Returns, ReturnTyping} from '#core/Type.js'
+import {Returns, ReturnType, ReturnTyping} from '#core/Type.js'
 import {match, Any} from '#core/TypePatterns.js'
 
-export const abs = match(Any, (math, T) => {
-   const absq = math.absquare.resolve(T)
-   const sqrt = math.sqrt.resolve(absq.returns, ReturnTyping.conservative)
-   return ReturnsAs(sqrt, t => sqrt(absq(t)))
+export const norm = match(Any, (math, T) => {
+   const normsq = math.normsq.resolve(T)
+   const sqrt = math.sqrt.resolve(
+      ReturnType(normsq), ReturnTyping.conservative)
+   return ReturnsAs(sqrt, t => sqrt(normsq(t)))
 })
+
+export const abs = norm // coincide for most types (scalars)
+
 export const conj = match(Any, (_math, T) => Returns(T, t => t))
+
 export const square = match(Any, (math, T, strategy) => {
    const mult = math.multiply.resolve([T, T], strategy)
-   return Returns(mult.returns, t => mult(t, t))
+   return ReturnsAs(mult, t => mult(t, t))
 })