Setup

$ npm init
$ npm install --save-dev @nomiclabs/buidler
$ npm install --save-dev @nomiclabs/buidler-ethers ethers
$ npm install --save-dev ts-node typescript
$ npm install --save-dev chai @types/node @types/mocha @types/chai
[create buidler.config.ts]
[create tsconfig.json]
[create scripts/Example1.ts]
[create scripts/Example2.ts]

buidler.config.ts

import { usePlugin } from "@nomiclabs/buidler/config"

usePlugin("@nomiclabs/buidler-ethers")

export default {}

tsconfig.json

{
    "compilerOptions": {
	"target": "es5",
	"module": "commonjs",
	"strict": true,
	"esModuleInterop": true,
	"outDir": "dist"
    },
    "include": ["./scripts", "./test"],
    "files": [
	"./buidler.config.ts",
	"./node_modules/@nomiclabs/buidler-ethers/src/type-extensions.d.ts"
    ]
}

Example 1

Given the following script:

import { ethers } from '@nomiclabs/buidler'

async function example (provider: ethers.providers.Provider) {
    let blockNumber = await provider.getBlockNumber()
    console.log(`Block number: ${blockNumber}`)
}

example(ethers.getDefaultProvider()).catch(console.error)

Attempting to run it fails during TypeScript compilation:

$ npx buidler run scripts/Example1.ts

TSError: Unable to compile TypeScript:
scripts/Example1.ts:3:35 - error TS2503: Cannot find namespace 'ethers'.

3 async function example (provider: ethers.providers.Provider) {

Example 2

Given the following script:

import { ethers } from 'ethers'

async function example (provider: ethers.providers.Provider) {
    let blockNumber = await provider.getBlockNumber()
    console.log(`Block number: ${blockNumber}`)
}

example(ethers.getDefaultProvider()).catch(console.error)

This example compiles and runs as expected.

$ npx buidler run scripts/Example2.ts
Block number: 9833062