Type instantiation is excessively deep and possibly infinite.

[RomanNabukhotnyi]

Hey! I have a large application using hono and I'm running into a problem with types.

Repo with a reproduction

In the main branch I moved all my routes and added one additional test route and then the error appeared.

In the test branch I moved all the routes from the modules into one file and was able to add 35 additional routes without this error.

I also managed to compare the difference between Hono and Elysia
With Elysia I was able to manage 1410 routes (470 routes / 3 instances) and with Hono - 120 (40 / 3).
Repo
I might miss or forget something here, in that case please let me know.

[yusukebe]

Hi @RomanNabukhotnyi !

Thanks for using Hono.

This problem is caused by the large number of routes. Elysia supports many routes, I'll see if I can improve Hono as well.

[flipvh]

Thank you @yusukebe ! As I can imagine this isn't trivial, you have perhaps ideas or tips to temporarily bypass this limit? Can we limit the RPC functionality or do we have to remove it completely for now, so we can continue to add more routes? Also, let me know if you think we can help. I could post a cleaner reproduction if that can help you? Please let me know, thnks again

[yusukebe]

Hi @flipvh

I'm struggling to improve the performance. Perhaps some improvement can be done by changing Types and fine tuning. But not easy to finish right now. So, please wait a moment.

As for bypassing the limit you mentioned, it would be a good idea to make the app smaller and create a client for each one.

For example, if you have the following application:

const appA = new Hono()
  .get('/1', (c) => c.json({ foo: 'bar ' }))
  .get('/2', (c) => c.json({ foo: 'bar ' }))
//...

const appB = new Hono()
  .get('/1', (c) => c.json({ foo: 'bar ' }))
  .get('/2', (c) => c.json({ foo: 'bar ' }))
//...

const oneApp = new Hono().route('/a', appA).route('/b', appB)
const client = hc<typeof oneApp>('http://localhost')

Just pass each app type to each client as follows:

const appA = new Hono()
  .get('/1', (c) => c.json({ foo: 'bar ' }))
  .get('/2', (c) => c.json({ foo: 'bar ' }))
//...

const appB = new Hono()
  .get('/1', (c) => c.json({ foo: 'bar ' }))
  .get('/2', (c) => c.json({ foo: 'bar ' }))
//...

const clientA = hc<typeof appA>('http://localhost/a')
const clientB = hc<typeof appB>('http://localhost/b')

[yusukebe]

Hi @RomanNabukhotnyi

I've added fix #2412, and the performance has improved a little. Then, it does not throw the error in your app:

But there is still improvement to be made as the hc function is not yet smart enough!

[RomanNabukhotnyi]

Thanks!