op for(start:integer, until:integer, by:integer, vars:ForVars, body:ForBody)->
	(ForVars*) =
    if start>until then
	nil
    else (
	let result = body(start, vars);
	for(start+by, until, by, vars, body) + [result]
    );
   
obj ForVars;
obj ForBody =  op(integer,ForVars)->(ForVars);
obj Vars < ForVars =  k:integer, result:integer;

op main(vars:Vars)->() =
(*begin*)
    for(1, 10, 1, vars (* alt will work with struct compat: {2, 1} *),
      lambda(i:integer, vars':Vars)->(vars'':Vars) (
	let result = vars.result * (i + vars.k);
	[vars.k, result]
      )
    )
(*end*);

(* OLD *)
op main_old()->() =
(*begin*)
    for(1, 10, 1, [2, 1],
      lambda(i:integer, k:integer, result:integer)->(integer,integer) (
	let result = result * (i + k);
	[k, result]
      )
    )
(*end*);