[fpc-pascal]How to call a variable of a procedural type?

[mili]

Hello, every body

  I write codes as the following:

>>>>>>>>
type TFunc = function : integer;

function myfunction:integer;
begin
  Result:=100;
end;//myfunction:

var
  fun : TFunc;
  a   : integer;
begin
  fun:=TFunc;
  a:=fun; //@1
  writeln(fun); //@2
end.

<<<<<<<<


  When I compile it, compiler report that at line of "@1" there's an error. 
But when I comment the line of "@1", the line of "@2" can work well.

  I don't know how to return the value of a procedural function variable. Can 
anybody tell me that? And tell me what's the different of lines between "@1" 
and "@2".

  Thank you,
  yours,
  mili