Incorrect Type Inference with mergeDeepRight, mergeDeepLeft, mergeRight, mergeLeft when Merging T and Partial<T>

[o-svetlichnyi]

Description:

After updating to the latest versions of ramda and @types/ramda, I encountered an issue with the type inference of the mergeDeepRight function in TypeScript. Specifically, when merging an object of type T with a Partial, the resulting type is not correctly inferred as T. Instead, properties are being inferred as unknown, leading to type errors.

This behavior did not occur in the previous versions (ramda@0.26.1 and @types/ramda@0.26.1), where the types were correctly inferred, and the merge operation worked without any type assertions or errors.

Affected Versions:

    "@types/ramda": "^0.30.2",
    "ramda": "^0.30.1",
    "typescript": "^5.5.4"

Reproduction:
https://stackblitz.com/edit/vitejs-vite-xsspwg?file=index.ts

[perrin4869]

I think the relevant change is this one: #129
I had the exact same problem