Promises are used most prominently in current-generation JavaScript where they lack a proper interface. Instead promises are standardized using language constru

Promises are used most prominently in current-generation JavaScript where they lack a proper interface. Instead promises are standardized using language constructs. Promises have the well-known disadvantage that promises are contagious, i.e, once a promise is used then everything that continues must be promises. On the other hand, a Future [Baker and Hewitt 1977] has the following well defined interface: Future<t> *interface* resolve[] ↦ t