Delphi equivalent of Haskell Tree

Haskell_tree.dpr

{$APPTYPE CONSOLE}
program haskell_tree_4;

type
  PMyTree = ^MyTree;
  MyTree  = record
     case b:boolean of
          false : ( );
          true  : ( Node        : integer;
                    Left, Right : PMyTree );
  end;

const     EmptyTree : MyTree = (b:false);

procedure print_tree(t:MyTree; indent:string);
const
  gap = '   ';
begin
  var indent2 := indent+gap;
  if t.b then begin
     writeln(indent,  t.Node);
     write  (indent2, 'Left  - ');  print_tree( t.Left^ , indent2);  writeln;
     write  (indent2, 'Right - ');  print_tree( t.Right^, indent2);  writeln;
  end
  else write(indent,'x');
end;

function  sum_tree  (t:MyTree):integer;
begin
  result := 0;
  case t.b of
     false : exit(0);
     true  : exit(result + t.Node
                         + sum_tree(t.Left^)
                         + sum_tree(t.Right^));
  end;
end;

function  make_tree (i:integer; const l,r:MyTree):MyTree;
begin
   with result do begin
       b     := true;
       node  := i;
       left  := @l;
       right := @r;
   end;
end;

begin
  writeln;

  var tree1 := make_tree(1, EmptyTree, EmptyTree);
  var tree2 := make_tree(2, EmptyTree, tree1);
  var tree3 := make_tree(3, make_tree(4, EmptyTree, EmptyTree), tree2);

  writeln('Node 3 (Node 4 Empty Empty) (Node 2 Empty (Node 1 Empty Empty))');
  writeln;
  print_tree( tree3, ''); writeln('Sum : ', sum_tree(tree3));
  writeln;
  print_tree( tree2, ''); writeln('Sum : ', sum_tree(tree2));
  writeln;
  print_tree( tree1, ''); writeln('Sum : ', sum_tree(tree1));
  writeln;
  readln;
end.