Incorrect ReadonlyArray.difference Override Referenced with flip

[JLambertazzo]

🐛 Bug report

Current Behavior

using flip from fp-ts/lib/function and ReadonlyArray.difference from fp-ts/ReadonlyArray

Applying flip to ReadonlyArray.difference uses the non-curried override of the difference method rather than the curried override. This results in the use of a deprecated flip override being used to to flip a non-curried method, and the resulting flipped function does not work as expected.

Below is on a fresh project after installing typescript and fp-ts:

Expected behavior

The flip function should use the curried version of ReadonlyArray.difference by using the non-deprecated version of flip.

Below is same code as above but using a custom curried difference function:

Reproducible example

See screenshots above

Suggested solution(s)

It seems weird to me that the deprecated override of a function is being used when the non-deprecated override can be used. Maybe there's a way to use the deprecated one only if the the non-deprecated override can't be applied?

Additional context

Your environment

Which versions of fp-ts are affected by this issue? Did this work in previous versions of fp-ts?

Using [email protected]. Haven't tried with previous versions

Software	Version(s)
fp-ts	2.13.1
TypeScript	4.8.4

[gcanti]

Maybe there's a way to use the deprecated one only if the the non-deprecated override can't be applied?

I'm not sure we can impose which override ts will choose in this specific case

[JLambertazzo]

Seems the preference comes from the order of signatures in the .d.ts file for ReadonlyArray. Tested with: Problem described above

Current order of function signatures in fp-ts

Proposed order of function signatures (deprecated first)

Result, non-deprecated function signature being used first