flow strict should allow unclear types for generics about flow HOT 6 CLOSED

For functions parameters, you will need contra-variance -. Note that ({...}) => mixed doesn't admit ({foo: string}) => mixed, since a function that calls f: ({...}) => mixed cannot be passed a callback that can only handle {foo: string} objects.

from flow.

Before we would just use {} (or {...}) but that's now gone

What do you mean by this? {...} is a good upper bound for all objects, if you want to include interfaces as well as objects, you can use interface {}

This page contains information you can find to specify the top types: https://flow.org/en/docs/lang/type-hierarchy/

from flow.

try flow

from flow.

Arrays are invariantly typed, so you need to use $ReadOnlyArray instead

from flow.

Invariants don't let you type function inputs though?

try flow

Or functions generally:

try flow

from flow.

The unclear-type error is there because these types are just any, which is inherently unsafe. It's conceptually the same as this lint rules, except that it's built in the checker itself. If you are unhappy with it, you can disable the lint

from flow.