UNITY is a programming language constructed by K. Mani Chandy and Jayadev Misra for their book Parallel Program Design: A Foundation.
It is a theoretical language which focuses on what, instead of where, when or how.
The language contains no method of flow control, and program statements run in a nondeterministic way until statements cease to cause changes during execution.
This allows for programs to run indefinitely, such as auto-pilot or power plant safety systems, as well as programs that would normally terminate (which here converge to a fixed point).
All statements are assignments, and are separated by #.
A statement can consist of multiple assignments, of the form a,b,c := x,y,z, or a := x || b := y || c := z.
You can also have a quantified statement list, <# x,y : expression :: statement>, where x and y are chosen randomly among the values that satisfy expression.
A quantified assignment is similar.
In <|| x,y : expression :: statement >, statement is executed simultaneously for all pairs of x and y that satisfy expression.
Bubble sort the array by comparing adjacent numbers, and swapping them if they are in the wrong order.
expected time,
processors and
expected work.
expected time, is that k is always chosen randomly from
This can be fixed by flipping k manually.
time with rank-sort.
Using the Floyd–Warshall algorithm all pairs shortest path algorithm, we include intermediate nodes iteratively, and get
The following programs computes all pairs shortest path in
, D[i,j] contains the length of the shortest path from
In the next round, of length