# typescript-transform-macros Typescript Transform Macros [](https://travis-ci.org/LeDDGroup/typescript-transform-macros) [](https://codeclimate.com/github/LeDDGroup/typescript-transform-macros/maintainability) [](https://codecov.io/gh/LeDDGroup/typescript-transform-macros) [](https://www.npmjs.com/package/typescript-transform-macros) [](https://github.com/prettier/prettier) [](https://conventionalcommits.org) [](http://spacemacs.org) Examples from . ## Installation ```sh npm install --save-dev typescript-transform-macros ``` ## Usage with [ttypescript](https://github.com/cevek/ttypescript/) Add it to _plugins_ in your _tsconfig.json_ ```json { "compilerOptions": { "plugins": [{ "transform": "typescript-transform-macros" }] } } ``` Also declare globally the _MACRO_ function: ```ts declare function MACRO(t: T): T; ``` ## Example _Input:_ ```ts declare function MACRO(t: T): T; const MAP = MACRO( ( inputConst: T[], visitor: (value: T, index?: number, input?: T[]) => L ) => { const input = inputConst; const length = input.length; const result = new Array(length) as L[]; for (let i = 0; i < length; i++) { result[i] = visitor(input[i], i, input); } return result; } ); declare interface Array { MAP: Array["map"]; } console.log([1, 2, 3].MAP(n => 3 * n + 1)); ``` _Output:_ ```js "use strict"; const input_1 = [1, 2, 3]; const length_1 = input_1.length; const result_1 = new Array(length_1); for (let i_1 = 0; i_1 < length_1; i_1++) { result_1[i_1] = 3 * input_1[i_1] + 1; } console.log(result_1); //> [ 4, 7, 10 ] ```