TypeScript + RxJS

hello.ts

import path = require('path');
import Git = require('nodegit');
import Rx = require('rx');

class Repo {
  private repo: Rx.Observable<Git.Repository>;

  constructor(private pathname: string) {
    this.repo = Rx.Observable.fromPromise(Git.Repository.open(pathname));
  }

  branches() {
    this.repo
      .flatMap(repository => repository.getCurrentBranch())
      .subscribe(reference => console.log(reference.name()))
    ;
  }
}

var dir: string = path.resolve('../path/to/git/repo');
var repo: Repo = new Repo(dir);

repo.branches();

// $ node hello.js 
// > refs/heads/master

node-git.d.ts

declare module "nodegit" {

  export class Reference {
    name(): string;
  }

  export class Repository {
    static open(path: string): Rx.IPromise<Repository>;
    getCurrentBranch(): Rx.IPromise<Reference>;
  }

}

rx-lite.d.ts

declare module Rx {
  declare module internals {
    ...
        export interface IPromise<T> {
          then<R>(onFulfilled: (value: T) => IPromise<R>, onRejected: (reason: any) => IPromise<R>): IPromise<R>;
          then<R>(onFulfilled: (value: T) => IPromise<R>, onRejected?: (reason: any) => R): IPromise<R>;
          then<R>(onFulfilled: (value: T) => R, onRejected: (reason: any) => IPromise<R>): IPromise<R>;
          then<R>(onFulfilled?: (value: T) => R, onRejected?: (reason: any) => R): IPromise<R>;
        }
    ...
  }
}

  }
}

tsconfig.json

{
    "compilerOptions": {
        "target": "es5",
        "module": "commonjs",
        "moduleResolution": "node",
        "isolatedModules": false,
        "jsx": "react",
        "experimentalDecorators": true,
        "emitDecoratorMetadata": true,
        "declaration": false,
        "noImplicitAny": false,
        "removeComments": true,
        "noLib": false,
        "preserveConstEnums": true,
        "suppressImplicitAnyIndexErrors": true
    },
    "filesGlob": [
        "**/*.ts",
        "**/*.tsx",
        "!node_modules/**"
    ],
    "files": [
        "hello.ts",
        "typings/node-git/node-git.d.ts",
        "typings/node/node.d.ts",
        "typings/rx/rx-lite.d.ts",
        "typings/rx/rx.d.ts"
    ],
    "exclude": []
}

Example of using TypeScript with an external library, and providing custom type definition files. This runs on Node.