have the corresponding right part evaluated.

ARITHMETIC EXPRESSION

   SYNTAX

      statement = conditional / unconditional;

      unconditional = loopst / cases / cibtrikst / uist / treest /
      block / null / exp;

      conditional = "IF" conjunct "THEN" unconditional (

         "ELSE" conditional /

         .empty);

      block = "begin" exp $('; exp) "end";

   An expressions may be a statement.  In conditional statements the
   else part is optional while in expressions it is mandatory.  This
   is a side effect of the way the left part of the syntax rules are
   ordered.

SEMI-TREE MANIPULATION AND TESTING

   SYNTAX

      treest = setpntr / insertpntr / deletepntr;

      setpntr = "set" "pointer" pntrname "to" pntrexp;

      pntrexp = direction pntrexp / pntrname;

      insertpntr = "insert" pntrexp "as"

         (("left" / "right") "brother") /

         (("first" / "last: ) "daughter") "of" pntrexp;

      direction =

         "up" /

         "down" /

         "forward" /

         "backward: /

         "head" /

         "tail";

      plantree = "replace" pntrname "with" pntrexp;

      deletepntr = "delete: pntrname;

      tree = '( tree1 ') ;

      tree1 = nodename $nodename ;

      nodename = terminal / '( tree1 ');

      terminal = treename / buffername / point ername;

      treename = id;

      treedecl = "pointer" .id / "tree" .id;

   Extra parentheses in tree building results in linear subcategorization,
   just as in LISP.

FLOW AND CONTROL

   controlst = gost / subst / loopstr / casest;

   GO TO STATEMENTS

      gost = "GO" "TO" (labelv / .id);

         assignlabel = "ASSIGN" .id "TO" labelv;

   SUBROUTINES

      subst = callst / returnst / cortnout;

         callst = "CALL" procname (exp / .emptyu);

         returnst = "RETURN" (exp / .empty);

         cortnout = "STUFF" exp "IN" pipename;

      cortnin = "FETCH" pipename;

      FETCH is a builtin function whose value is computed by envoking
      the named co-routine.

   LOOP STATEMENTS