feat: Introduce BooleanT and boolean functions (#17)

This PR adds a boolean section, as well as an isNaN predicate on numbers. In a TypeDispatcher, when BooleanT is present, isNaN returns a BooleanT. However, in a numbers-only TypeDispatcher, it returns 1 or 0 instead. Moreover, when booleans are subsequently added to a numbers-only instance, isNaN properly reconfigures itself to return BooleanT.

No predicates that depend on approximate equality testing or a configuration object are implemented in this PR.

This PR also implements type matching and dispatching with implicit conversions, and adds an implicit conversion from BooleanT to NumberT.

Reviewed-on: #17
Co-authored-by: Glen Whitney <glen@studioinfinity.org>
Co-committed-by: Glen Whitney <glen@studioinfinity.org>

src/boolean/BooleanT.js

@@ -0,0 +1,3 @@
+import {Type} from '#core/Type.js'
+
+export const BooleanT = new Type(n => typeof n === 'boolean')

src/boolean/__test__/BooleanT.spec.js

@@ -0,0 +1,24 @@
+import assert from 'assert'
+import {BooleanT} from '../BooleanT.js'
+import math from '#nanomath'
+
+describe('BooleanT Type', () => {
+   it('correctly recognizes booleans', () => {
+      assert(BooleanT.test(true))
+      assert(BooleanT.test(false))
+      assert(!BooleanT.test(null))
+      assert(!BooleanT.test(1))
+   })
+   it('autoconverts to number type', () => {
+      assert.strictEqual(math.abs(false), 0)
+      assert.strictEqual(math.absquare(true), 1)
+      assert.strictEqual(math.add(true, true), 2)
+      assert.strictEqual(math.divide(false, true), 0)
+      assert.strictEqual(math.cbrt(true), 1)
+      assert.strictEqual(math.invert(true), 1)
+      assert.strictEqual(math.multiply(false, false), 0)
+      assert.strictEqual(math.negate(false), -0)
+      assert.strictEqual(math.subtract(false, true), -1)
+      assert.strictEqual(math.quotient(true, true), 1)
+   })
+})

src/boolean/__test__/type.spec.js

@@ -0,0 +1,25 @@
+import assert from 'assert'
+import math from '#nanomath'
+import {Type} from '#core/Type.js'
+
+const boolean = math.boolean
+
+describe('boolean type functions', () => {
+   it('properly converts to boolean', () => {
+      assert.strictEqual(boolean(false), false)
+      assert.strictEqual(boolean(true), true)
+      assert.strictEqual(boolean(0), false)
+      assert.strictEqual(boolean(-0), false)
+      assert.strictEqual(boolean(NaN), false)
+      assert.strictEqual(boolean(Infinity), true)
+      assert.strictEqual(boolean(1e-30), true)
+      assert.strictEqual(boolean(undefined), false)
+      assert.strictEqual(boolean(), false)
+      assert.strictEqual(boolean(math.types.NumberT), true)
+   })
+   it('converts any type to boolean', () => {
+      for (const T in math.types) {
+         if (T instanceof Type) assert(boolean.resolve([T]))
+      }
+   })       
+})

src/boolean/all.js

@@ -0,0 +1,2 @@
+export * as typeDefinition from './BooleanT.js'
+export * as type from './type.js'

src/boolean/type.js

@@ -0,0 +1,14 @@
+import {BooleanT} from './BooleanT.js'
+import {onType} from '#core/helpers.js'
+import {Returns, Type, TypeOfTypes, Undefined} from '#core/Type.js'
+import {NumberT} from '#number/NumberT.js'
+
+const bool = f => Returns(BooleanT, f)
+
+export const boolean = onType(
+   BooleanT, bool(p => p),
+   NumberT, bool(a => !!a),
+   TypeOfTypes, bool(() => true),
+   Undefined, bool(() => false),
+   [], bool(() => false)
+)