immutable + xstream

const { Map } = require('immutable@4.0.0-rc.12') const xs = require('xstream').default; const m = Map() const set = m.set('a', xs.empty()) const upd = m.update('a', xs.empty(), s => s) console.log(set) // Map {"a" => Stream {_d: false, _dl: Object {}, _err: Object {}, _ils: [], …}} console.log(upd) // Map {}