feat: initial commit

Author: danielpza

.gitignore

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+dist/
+node_modules/

LICENSE

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+MIT License
+
+Copyright (c) 2018 LeDDGroup
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# typescript-conditional-types
+
+[![npm version](https://img.shields.io/npm/v/typescript-conditional-types.svg)](https://www.npmjs.com/package/typescript-conditional-types)
+[![Conventional Commits](https://img.shields.io/badge/Conventional%20Commits-1.0.0-yellow.svg)](https://conventionalcommits.org)
+[![code style: prettier](https://img.shields.io/badge/code_style-prettier-ff69b4.svg?style=flat-square)](https://github.com/prettier/prettier)
+
+Helpers for typescript generic types
+
+## Motivation
+
+Creating complex types with conditional types ( `T extends U ? X : Y` ) could be a little verbose. This package aims to simplify code and make it more readable.
+
+Instead of
+
+```ts
+type ComplexType<A> = A extends boolean
+  ? number
+  : A extends number ? number : string
+  : string
+```
+
+You could write
+
+```ts
+type ComplexType<A> = If<
+  Or<Extends<A, number>, Extends<A, boolean>>,
+  number,
+  string
+>;
+```
+
+## Install
+
+```bash
+$ npm install typescript-conditional-types
+```
+
+You'll probably want to save it in the _devDependencies_
+
+## Type Helper List
+
+- _If<Condition, Then, Else>_: If _Condition_ is `true` resulting type is _Then_ else _Else_
+- _And<A, B>_: `true` if _A_ and _B_ are both `true` else `false`
+- _Or<A, B>_: `true` if _A_ or _B_ are `true` else `false`
+- _Not<A>_: Negate _A_
+- _Extends<A, B>_: `true` if _A_ extends _B_ like in `A extends B ? true : false`
+- _Extends<A, B, Then, Else_: Equivalent to `If<Extends<A, B>, Then, Else>`
+
+## Usage Example
+
+```ts
+import { If } from "typescript-conditional-types";
+
+type BooleanToString<T extends boolean> = If<T, "true", "false">
+
+BooleanToString<true> // "true"
+BooleanToString<false> // "false"
+```