feat(types): Float, Integer

Signed-off-by: Lexus Drumgold <[email protected]>

src/types/__tests__/float.spec-d.ts

@@ -0,0 +1,17 @@
+/**
+ * @file Type Tests - Float
+ * @module tutils/types/tests/unit-d/Float
+ */
+
+import type TestSubject from '../float'
+import type { tag } from '../opaque'
+
+describe('unit-d:types/Float', () => {
+  it('should extend number', () => {
+    expectTypeOf<TestSubject>().toMatchTypeOf<number>()
+  })
+
+  it('should match [readonly [tag]: "float"]', () => {
+    expectTypeOf<TestSubject>().toMatchTypeOf<{ readonly [tag]: 'float' }>()
+  })
+})

src/types/__tests__/integer.spec-d.ts

@@ -0,0 +1,17 @@
+/**
+ * @file Type Tests - Integer
+ * @module tutils/types/tests/unit-d/Integer
+ */
+
+import type TestSubject from '../integer'
+import type { tag } from '../opaque'
+
+describe('unit-d:types/Integer', () => {
+  it('should extend number', () => {
+    expectTypeOf<TestSubject>().toMatchTypeOf<number>()
+  })
+
+  it('should match [readonly [tag]: "integer"]', () => {
+    expectTypeOf<TestSubject>().toMatchTypeOf<{ readonly [tag]: 'integer' }>()
+  })
+})

src/types/__tests__/opaque.spec-d.ts

@@ -4,20 +4,17 @@
  */
 
 import type TestSubject from '../opaque'
+import type { tag } from '../opaque'
 
 describe('unit-d:types/Opaque', () => {
   type B = number
   type T = 'account-number'
 
-  it('should be assignable to type of B', () => {
+  it('should extend B', () => {
     expectTypeOf<TestSubject<B, T>>().toMatchTypeOf<B>()
   })
 
-  it('should not match opaque type with same base and different token', () => {
-    // Arrange
-    type T2 = 'account-balance'
-
-    // Expect
-    expectTypeOf<TestSubject<B, T>>().not.toMatchTypeOf<TestSubject<B, T2>>()
+  it('should match [readonly [tag]: T]', () => {
+    expectTypeOf<TestSubject<B, T>>().toMatchTypeOf<{ readonly [tag]: T }>()
   })
 })

src/types/float.ts

@@ -0,0 +1,15 @@
+/**
+ * @file Type Definitions - Float
+ * @module tutils/types/Float
+ */
+
+import type Opaque from './opaque'
+
+/**
+ * A floating point number.
+ *
+ * @see https://computersciencewiki.org/index.php/float
+ */
+type Float = Opaque<number, 'float'>
+
+export type { Float as default }

src/types/index.ts

@@ -19,6 +19,7 @@ export type { default as EnsureString } from './ensure-string'
 export type { default as ExactOptionalPropertyTypes } from './exact-optional-property-types'
 export type { default as Fallback } from './fallback'
 export type { default as FIXME } from './fixme'
+export type { default as Float } from './float'
 export type { default as Fn } from './fn'
 export type { default as Get } from './get'
 export type { default as IfAny } from './if-any'
@@ -40,6 +41,7 @@ export type { default as IfUndefined } from './if-undefined'
 export type { default as IfUnknown } from './if-unknown'
 export type { default as IndexSignature } from './index-signature'
 export type { default as Indices } from './indices'
+export type { default as Integer } from './integer'
 export type { default as IsAny } from './is-any'
 export type { default as IsArray } from './is-array'
 export type { default as IsBigInt } from './is-big-int'

src/types/integer.ts

@@ -0,0 +1,16 @@
+/**
+ * @file Type Definitions - Integer
+ * @module tutils/types/Integer
+ */
+
+import type Opaque from './opaque'
+
+/**
+ * A number that can be negative, positive, or zero, but not a fraction (i.e.
+ * cannot have a decimal point).
+ *
+ * @see https://computersciencewiki.org/index.php/int
+ */
+type Integer = Opaque<number, 'integer'>
+
+export type { Integer as default }

src/types/opaque.ts

@@ -4,9 +4,9 @@
  */
 
 /**
- * Token symbol for {@linkcode Opaque}.
+ * {@linkcode Opaque} type token key.
  */
-declare const token: unique symbol
+export declare const tag: unique symbol
 
 /**
  * Creates an [opaque type][1].
@@ -17,11 +17,15 @@ declare const token: unique symbol
  * The type token parameter, `T`, allows TypeScript to differentiate between
  * opaque types with the same base type.
  *
- * [1]: https://codemix.com/opaque-types-in-javascript/
+ * [1]: https://codemix.com/opaque-types-in-javascript
+ *
+ * @see https://github.com/Microsoft/TypeScript/issues/202
+ * @see https://github.com/Microsoft/TypeScript/issues/15408
+ * @see https://github.com/Microsoft/TypeScript/issues/15807
  *
  * @template B - Base type
  * @template T - Type token
  */
-type Opaque<B, T = unknown> = B & { readonly [token]: T }
+type Opaque<B, T = unknown> = B & { readonly [tag]: T }
 
 export type { Opaque as default }