Why are the interface declarations invariant?

[arturaz]

It seems that after adding this compiles just fine:

diff --git a/src/vanilla/atom.ts b/src/vanilla/atom.ts
index 2a8239d..784591a 100644
--- a/src/vanilla/atom.ts
+++ b/src/vanilla/atom.ts
@@ -39,7 +39,7 @@ type OnMount<Args extends unknown[], Result> = <
   setAtom: S,
 ) => OnUnmount | void
 
-export interface Atom<Value> {
+export interface Atom<out Value> {
   toString: () => string
   read: Read<Value>
   debugLabel?: string
@@ -60,8 +60,8 @@ export interface Atom<Value> {
 }
 
 export interface WritableAtom<
-  Value,
-  Args extends unknown[],
+  out Value,
+  in Args extends unknown[],
   Result,
 > extends Atom<Value> {
   read: Read<Value, SetAtom<Args, Result>>

[dai-shi]

Variance annotations are not supported in old TS versions. We currently support >= 3.8.

jotai/package.json

Line 28 in 83dce49

"ts_version_3.8_and_above_is_required.d.ts"

We are going to drop old TS versions for the upcoming Jotai v3.
It's a good hint that we should at least drop < 4.7. https://devblogs.microsoft.com/typescript/announcing-typescript-4-7/#optional-variance-annotations-for-type-parameters