Composition of Lenses do not type properly

[marcoemrich]

Issue

Composing functions of type R.Lens do not provide a proper Lens-Type.

Example:

const quantityLens = R.lensProp('quantity')
const composedLens = R.compose(quantityLens)
const result1 = R.view(quantityLens, {quantity: 5}) // this works
const result2 = R.view(composedLens, { quantity: 5 }) // this results in TS error (see screenshot)

One-Liner to demo the issue

const composedLens: R.Lens = R.compose(R.lensProp('foo')) 

Error:
Property 'set' is missing in type '(obj: unknown) => unknown' but required in type 'Lens'.ts(2741)

Maybe this is expected behavior. But it does work in Ramda - in that case, consider it a feature request instead of a bug.

Rambda version

8.6.0

Node.js version

20.6.1

[selfrefactor]

I will sync with Ramda types and this should be fixed. I will post update as soon as I have it.

[selfrefactor]

I will need also your TS version. I did test with latest TS and this is what I see:

not sure how to proceed further

[marcoemrich]

TS-Version is 5.3.3

But isn't the import in the screenshot above coming from Ramda instead of Rambda?

[selfrefactor]

I wanted to first check how your example works in Ramda, so that I can aim for similar result

[marcoemrich]

The Ramda version needs the generics type info to work

import * as R from 'ramda'

const quantityLens = R.lensProp<{ quantity: number }, 'quantity'>('quantity')
const composedLens = R.compose(quantityLens)
const result1 = R.view(quantityLens, { quantity: 5 })
const result2 = R.view(composedLens, { quantity: 5 })

[marcoemrich]

The fact that rambda does not need the annotation <{ quantity: number }, 'quantity'>, I would consider one of the big advantages of rambda over ramda

[selfrefactor]

I used your latest example with Rambda code. It is not great as result1 is unknown, which led me to decision to change Rambda types with ramda.

If you have better suggestion how to fix this without this big change, I am open to your feedback.

As I don't use lenses that much, I am not the best source for the correctness of their types, so I will do the fastest solution which is to sync.

[selfrefactor]

released with 9.0.0
this issue is the reason for the breaking change as types of lenses are synced with ramda