feat(utilities): add possibility to import single functions by appending them to the import path.

[imranbarbhuiya]

fixes #452

tsup was bunding the dts in one file and has no option to disable it. So I've used tsc to build the types files.

[imranbarbhuiya]

Not sure why build is failing with targe 2021

[favna]

Granted even CJS didn't work before my commit above this review, this PR still needs more work.

Create a file on the root of the repository called test.cjs with content:

/* eslint-disable @typescript-eslint/no-var-requires */
const { isFunction } = require('@sapphire/utilities/isFunction');

console.log(isFunction(() => undefined));

then run it with node test.cjs. This will return true as expected.

However doing the same with test.mjs and content:

import { isFunction } from '@sapphire/utilities/isFunction';

console.log(isFunction(() => undefined));

will give:

node file.mjs
file:///Users/favna/workspace/sapphire/utilities/file.mjs:1
import { isFunction } from '@sapphire/utilities/isFunction';
         ^^^^^^^^^^
SyntaxError: Named export 'isFunction' not found. The requested module '@sapphire/utilities/isFunction' is a CommonJS module, which may not support all module.exports as named exports.
CommonJS modules can always be imported via the default export, for example using:

import pkg from '@sapphire/utilities/isFunction';
const { isFunction } = pkg;

    at ModuleJob._instantiate (node:internal/modules/esm/module_job:123:21)
    at async ModuleJob.run (node:internal/modules/esm/module_job:189:5)
    at async Promise.all (index 0)
    at async ESMLoader.import (node:internal/modules/esm/loader:528:24)
    at async loadESM (node:internal/process/esm_loader:91:5)
    at async handleMainPromise (node:internal/modules/run_main:65:12)

Node.js v18.8.0

And lastly, TS is also broken, again with a similar file this time file.ts:

import { isFunction } from '@sapphire/utilities/isFunction';

console.log(isFunction(() => undefined));

This gives a compiler error:

Cannot find module '@sapphire/utilities/isFunction' or its corresponding type declarations.ts(2307)

[favna]

blocking until #468 is merged

resolved