Should we use is-stream package?

[phated]

We currently use instanceof to check if something is a stream. However, the is-stream module on npm uses stream !== null && typeof stream === 'object' && typeof stream.pipe === 'function'; should we switch to the external module?

cc @contra @sindresorhus

[sindresorhus]

Not all compatible streams inherit from Stream, and even if they do, instanceof doesn't work across realms (vm module contexts).

[darsain]

Yes, definitely ducktype it. instanceof causes issues in so many places.

[phated]

On the other hand, people stick pipe onto things that aren't fully streams compatible (see merge in event-stream). We've had to de-support libraries like event-stream because of that.

I do agree that instanceof is generally bad.

[phated]

I'd like to get @contra's thoughts though.

[yocontra]

Yeah, checking for .pipe is good enough for me - instanceof sucks.

[phated]

Done