The ability to define virtual DOM structure in one place and have it render in another

m.Portal.js

const Portal = {
  view : ({attrs, content = []}) =>
    attrs.view({
      outlet: () => 
        content,

      inlet: (...input) => {
        content.splice(0, Infinity, ...input)
      },
    }) 
}

try{ module.exports = Portal } catch(e){}

Streams are an unnecessary dependency and introduce too much ambiguity. Inlet is just a setter. Outlet is just a getter. Remove the dep and make the code more explicit.