Rule prefer-immutable-types doesn't work with fp-ts Types

[ldrick]

Bug Report

If you use fp-ts ReadonlyNonEmptyArray (https://gcanti.github.io/fp-ts/modules/ReadonlyNonEmptyArray.ts.html) like this:

import {readonlyNonEmptyArray as RNEA} from 'fp-ts';

const myMethod= (
	values: RNEA.ReadonlyNonEmptyArray<number>,
): RNEA.ReadonlyNonEmptyArray<string> => RNEA.map(/* some code*/)(values)

Expected behavior

The parameter values: RNEA.ReadonlyNonEmptyArray<number> should be detected as being immutable.

Actual behavior

The parameter values: RNEA.ReadonlyNonEmptyArray<number> gets marked as being mutable.
Rewriting the above to somehow fixes the error, but looks not quite right:

import {readonlyNonEmptyArray as RNEA} from 'fp-ts';

const myMethod= (
	values: Readonly<RNEA.ReadonlyNonEmptyArray<number>>,
): RNEA.ReadonlyNonEmptyArray<string> => RNEA.map(/* some code*/)(values)

Steps to reproduce

use above sample

Proposed changes

Maybe, as I don't know the details, somehow check, if the Type is a superior Type of immutable types?

[RebeccaStevens]

Looks like this is a bug in the upstream library. I've open an issue for it over there (is-immutable-type#40).

In the meantime, one possible work around is to use an immutability override to mark ReadonlyNonEmptyArray as ReadonlyShallow:

"settings": {
  "immutability": {
    "overrides": [
      {
        "name": "ReadonlyNonEmptyArray",
        "to": "ReadonlyShallow",
        "from": "Mutable"
      }
    ]
  }
}

[RebeccaStevens]

Fixed in the upstream now.