-- This example illustrates how to program TAIL and HEAD 
-- functions in RIGAL.
 #MAIN
  $E:=(. ALFA BETA GAMMA DELTA .);
 OPEN S ' ';   -- Opens file S for output to the screen
 S<<$E;
 S<<'HEAD=' #HEAD($E);
 S<<'TAIL=' #TAIL($E);
 $W:=<. SEL1 : $E,
        SEL2 : #HEAD($E),
        SEL3 : #TAIL($E) .>;
 PRINT $W;
##
#HEAD 
  (. $E   (* $A *) .) / RETURN $E / ##
#TAIL
  (. $A   (* $L!.:=$E *) .) /RETURN $L /##