Seven Obscure Languages in Seven Weeks

Replicating Processes

Occam processes are fantastic; Occam arrays are fabulous. Why don’t we combine them and get something even better—arrays of processes? Occam supports them via process replication.

Let’s look again at the code example and revisit the problem, “What if you want to multiplex N=128 channels? Should you copy the block N=128 times?” No, you should instruct Occam to replicate the highlighted block N times:

  ALT
    enabled.i & src.i ? x
      dest ! x
...

The result is a process replication (also highlighted in the following example):

occam/mux.occ

VAL N IS 128:
PROC mux ()
  CHAN OF INT dest:
  [N]CHAN OF INT src:
  [N]BOOL enabled:
  INT x:

  WHILE TRUE
    -- The replicated part
    ALT i=0 FOR ...