Felleisen, MatthiasFlanagan, Cormac2017-08-022017-08-021994-10Felleisen, Matthias and Flanagan, Cormac. "The Semantics of Futures." (1994) https://hdl.handle.net/1911/96445.https://hdl.handle.net/1911/96445The future annotation introduced by MultiLisp provides a simple method for taming the implicit parallelism of functional programs. Prior research on futures has concentrated on implementation and design issues, and has largely ignored the development of a semantic characterization of futures. This paper presents four operational semantics for an idealized functional language with futures with varying degrees of intensionality. The first semantics defines future to be a semantically-transparent annotation. The second semantics interprets a future expression as a potentially parallel task. The third semantics explicates the coordination of parallel tasks and the need for touch operations on placeholder-strict arguments to certain primitive operations by introducing placeholder objects. The fourth and last semantics is a low-level refinement of the third semantics, which explicates just enough information to permit the smooth derivation of program analyses. The paper includes proofs showing the equivalence of these semantics.38 ppengYou are granted permission for the noncommercial reproduction, distribution, display, and performance of this technical report in any format, but this permission is only for a period of forty-five (45) days from the most recent time that you verified that this technical report is still available from the Computer Science Department of Rice University under terms that include this permission. All other rights are reserved by the author(s).Technical reportTR94-238