declare
C={NewCell 0}
{Browse C}
{Browse [val @C]}
{Exchange C 2 1}

declare
fun {Reverse Xs}
   Rs={NewCell nil}
in for X in Xs do Rs := X|@Rs end
   @Rs
end
{Browse {Reverse [1 2 3 4]}}

declare   
fun {Reverse Xs}
   {FoldL Xs fun {$ Z E} E|Z end nil}
%   {FoldR Xs fun {$ E Z} NewZ in Z=E|NewZ NewZ end $ nil}
end
{Browse {Reverse [1 2 3 4]}}

%------------------
declare
C={NewCell 1}
D={NewCell 2}
proc {Swap X0 Y0}
   X={NewCell @X0}
   Y={NewCell @Y0} in
   X:=@X + @Y
   Y:=@X - @Y
   X:=@X - @Y
   X0:=@X
   Y0:=@Y
end
in {Browse [@C @D]}
{Swap C D} {Browse [@C @D]}
{Swap C C} {Browse [@C @C]}

%----Call by ref -------
declare
proc {ParamTest X}
   X=5
end
Z in
{Show Z}
{ParamTest Z} %5
{Show Z}

%----Call by name -------
declare X=3
 fun {P X Y} {Y} end
 fun {Q X Y} {X} end
in {Browse {Q fun {$} 2 end
	      fun {$} X end}}

declare
 proc {Sqr A}
    {A}:=@{A} * @{A}
 end
 local C={NewCell 5} in
    {Sqr fun {$} C end}
    {Browse @C}
 end

%----Call by need ----
declare
proc {Sqr A0}
   A={NewCell @A0} in
   {A}:=@{A} * @{A}
end
local C={NewCell 5} in
   {Sqr fun {$} C end} % can be implemented with lazy functions
   {Browse @C}
end