@record myrec { field1, field2 };

x = myrec(1,2);

switch (x) {
  @match myrec(field1=1): // matches
    switch (x) {
      @match myrec(field2=y): printf("ok, y = %d\n",y); break; // matches
    }
    break;
}

switch (x) {
         @match myrec(): printf("ok\n"); break;
}

switch (x) {
       @match myrec(1): break; // not enough fields, won't match
       @match myrec(field2=1): break; // wrong value
       @match myrec(field2=2,field1=x): printf("ok, x = %d\n", x); break;
}