Using pure structures

A pure structure is a user-defined data type that contains only int/bool or other pure structures. An example of a pure structure is:

deftype cache_entry (bool valid; int<32> data; int<24> tag) { }

An example CHP program that uses this as the data type is:

defproc cache(chan?(int<32>) A; chan?(bool) RD; chan!(int<32>) DI; chan!(int<32>) DO)
{
   cache_entry C[256];
   int<32> addr;
   bool cmd;
   cache_entry ce;
 
   chp {
     *[ A?addr,RD?cmd;
        [cmd -> // read command
                       ce := C[addr{7..0}];
                     [ ce.valid & ce.tag = addr{31..8} -> log ("cache hit!"); DO!ce.data
                     [] else -> log ("cache miss!"); DO!0
                     ]
     []~cmd -> // write command
                  ce.valid+;
                  DI?ce.data;
                  ce.tag := addr{31..8};
                  C[addr{7..0}] := ce
      ]
   ]
  }                  
}

(Note: this is not meant to be a working cache!)