Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Janus (time-reversible computing programming language)
open-in-new
<p>Janus is a <a href="/facts/Reversible_computing/yEum13Vs">time-reversible</a> programming language written at <a href="/facts/Caltech/3FPcp7BL">Caltech</a> in 1982. The <a href="/facts/Operational_semantics/G24LXz6e">operational semantics</a> of the language were formally specified, together with a program inverter and an invertible <a href="/facts/Self-interpreter/JB85fbyb">self-interpreter</a>, in 2007 by Tetsuo Yokoyama and Robert Glück. A Janus inverter and interpreter is made freely available by the <a href="/facts/TOPPS_(research_group)/njRzX8QS">TOPPS research group</a> at <a href="/facts/DIKU/TC9QpGrC">DIKU</a>. Another Janus interpreter was implemented in <a href="/facts/Prolog/r5h66Qh1">Prolog</a> in 2009. An optimizing compiler has been developed in the RC3 research group. The below summarises the language presented in the 2007 paper. </p><p>Janus is a structured imperative programming language that operates on a global store without heap allocation and does not support dynamic data structures. As a reversible programming language, Janus performs deterministic computations in both forward and backward directions. An extension of Janus features procedure parameters and local variable declarations (local-delocal). Additionally, other variants of Janus support dynamic data structures such as lists. </p>