@coderspirit/lambda-ioc

Pure functional (λ) dependency injection 💉 for TypeScript (inspired by Diddly)

NOTE: This is a “fork” of Tom Sherman’s Diddly library, who deserves most credit for this work.

Install instructions

Node

# With NPM
npm install @coderspirit/lambda-ioc

# Or with Yarn:
yarn add @coderspirit/lambda-ioc

Deno

Lambda-IoC is served through different CDNs

import { ... } from 'https://denopkg.com/Coder-Spirit/lambda-ioc@[VERSION]/lambda-ioc/deno/index.ts'
import { ... } from 'https://deno.land/x/lambda_ioc@[VERSION]/lambda-ioc/deno/index.ts'

Benefits

  • 100% type safe:
    • The type checker will complain if we try to resolve unregistered dependencies.
    • The type checker will complain if we try to register new dependencies that depend on unregistered dependencies, or if there is any kind of type mismatch.
  • Purely functional
  • Immutable
  • Circular dependencies are impossible

Drawbacks

  • All dependencies must be declared “in order”.
    • This implies that this IoC container cannot be used in combination with some auto-wiring solutions, such as IoC decorators.
  • The involved types are a bit convoluted:
    • They might cause the type checker to be slow.
    • In some situations, the type checker might be unable to infer the involved types due to excessive “nested types” depth.

Example

import { createContainer } from '@coderspirit/lambda-ioc'

function printNameAndAge(name: string, age: number) {
  console.log(`${name} is aged ${age}`)
}
​
const container = createContainer()
  .register('someAge', value(5))
  .register('someName', value('Timmy'))
  .register('fn', func(printNameAndAge, 'someName', 'someAge'))
​
const print = container.resolve('fn')
print() // Prints "Timmy is aged 5"