✨ Add not function

docs/api/falsy/index.md

@@ -0,0 +1,16 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+
+
+## Falsy type
+
+> This API is provided as a preview for developers and may change based on feedback that we receive. Do not use this API in a production environment.
+> 
+
+Alias for Falsy values
+
+<b>Signature:</b>
+
+```typescript
+type Falsy = false | "" | 0 | null | undefined;
+```

docs/api/index.md

@@ -44,6 +44,7 @@
 |  [lt](./lt/) | Returns <code>true</code> if the first argument is less than the second; otherwise <code>false</code> |
 |  [lte](./lte/) | Returns <code>true</code> if the first argument is less than or equal to the second; otherwise <code>false</code> |
 |  [multiply](./multiply/) | Multiplies first argument and second argument. |
+|  [not](./not/) | <b><i>(BETA)</i></b> Returns the <code>!</code> of its argument. |
 |  [or](./or/) | Returns true if one or both of its arguments are true; otherwise false. |
 |  [prepend](./prepend/) | Returns a new list with the given value at the front, followed by the contents of the list. |
 |  [product](./product/) | Multiplies together all the elements of a list. |
@@ -65,6 +66,7 @@
 |  [AnyFn](./anyfn/) | Type of any function |
 |  [Empty](./empty/) | <b><i>(BETA)</i></b> Alias for Empty values |
 |  [endsWith](./endswith/) |  |
+|  [Falsy](./falsy/) | <b><i>(BETA)</i></b> Alias for Falsy values |
 |  [Ord](./ord/) | Abbreviation for Ordinal |
 |  [Primitive](./primitive/) | Alias for Primitive values types |
 

docs/api/not/index.md

@@ -0,0 +1,36 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+
+
+## not variable
+
+> This API is provided as a preview for developers and may change based on feedback that we receive. Do not use this API in a production environment.
+> 
+
+Returns the `!` of its argument.
+
+<b>Signature:</b>
+
+```typescript
+not: <T>(val: T) => T extends Falsy ? true : boolean
+```
+
+## Remarks
+
+The Definition of Falsy - `''` - `false` - `0` - `NaN` - `undefined` - `null`
+
+## Example
+
+
+```ts
+not('') // true
+not(false) // true
+not(0) // true
+not(NaN) // true
+not(undefined) // true
+not(null) // true
+
+not({}) // false
+
+```
+

mod.ts

@@ -35,6 +35,7 @@ export { lowerCase } from './src/lowerCase.ts'
 export { lt } from './src/lt.ts'
 export { lte } from './src/lte.ts'
 export { multiply } from './src/multiply.ts'
+export { not } from './src/not.ts'
 export { or } from './src/or.ts'
 export { prepend } from './src/prepend.ts'
 export { product } from './src/product.ts'
@@ -45,7 +46,7 @@ export { sum } from './src/sum.ts'
 export { T } from './src/T.ts'
 export { tail } from './src/tail.ts'
 export { trim } from './src/trim.ts'
-export type { AnyFn, Empty, Ord, Primitive } from './src/types.ts'
+export type { AnyFn, Empty, Falsy, Ord, Primitive } from './src/types.ts'
 export { upperCase } from './src/upperCase.ts'
 export { values } from './src/values.ts'
 export { xor } from './src/xor.ts'

src/not.ts

@@ -0,0 +1,33 @@
+import { Falsy } from './types/index.ts'
+/**
+ * Returns the `!` of its argument.
+ *
+ * @param val - input any value
+ * @returns The result of `!val`
+ *
+ * @remarks
+ * The Definition of Falsy
+ * - `''`
+ * - `false`
+ * - `0`
+ * - `NaN`
+ * - `undefined`
+ * - `null`
+ *
+ * @example
+ * ```ts
+ * not('') // true
+ * not(false) // true
+ * not(0) // true
+ * not(NaN) // true
+ * not(undefined) // true
+ * not(null) // true
+ *
+ * not({}) // false
+ * ```
+ *
+ * @beta
+ */
+const not = <T>(val: T): T extends Falsy ? true : boolean =>
+  !val as T extends Falsy ? true : boolean
+export { not }

src/types/index.ts

@@ -38,5 +38,12 @@ export type Ord = string | number | bigint | boolean | Date
 // eslint-disable-next-line @typescript-eslint/ban-types
 export type Empty = '' | [] | {}
 
+/**
+ * Alias for Falsy values
+ *
+ * @beta
+ */
+export type Falsy = false | '' | 0 | null | undefined
+
 export type InferArray<T> = T extends (infer R)[] ? R : never
 export type Whitespace = ' ' | '\t' | '\n'

test/not.spec.ts

@@ -0,0 +1,23 @@
+import { not } from '@/not'
+
+describe('not', () => {
+  const table: [unknown, boolean][] = [
+    ['', true],
+    [undefined, true],
+    [null, true],
+    [0, true],
+    [NaN, true],
+    [false, true],
+    [[], false],
+    [{}, false],
+    ['hello', false],
+    [Infinity, false],
+    [1, false],
+    [-1, false],
+    [true, false]
+  ]
+
+  it.each(table)('not(%s) -> %s', (val, expected) => {
+    expect(not(val)).toBe(expected)
+  })
+})