https://discordapp.com/channels/291054398077927425/453733491067322378/585326188944293928 Publisherという名前からも、Reactive Streamsに寄せている感じがある ForumでTony Parkerが "Combine is indeed based on the Reactive Streams spec, with a few small modifications that we felt were important." と書いてますね。 https://forums.swift.org/t/will-swiftnio-adapt-to-the-new-combine-framework/25166/11

Combine is indeed based on the Reactive Streams spec, with a few small modifications that we felt were important.