From: ruvim.pinka@gmail.com   
      
   On 2024-05-29 06:21, dxf wrote:   
   > On 29/05/2024 3:39 am, Ruvim wrote:   
   >> On 2024-05-24 15:56, Anton Ertl wrote:   
   >>> melahi_ahmed@yahoo.fr (Ahmed) writes:   
   >>>>   
   >>>>    In Forth it is a bit messier because you   
   >>>>    want a signature like   
   >>>>   
   >>>>   
   >>>>     : d/dx ( xt -- xt ) .... ;   
   >>>   
   >>> Most probably he meant ( xt1 -- xt2 )   
   >>   
   >>   
   >>   
   >> Do you mean that ( xt -- xt ) is an incorrect stack diagram for this case?   
   >>   
   >> I always thought that such use is correct. Because formally "xt" (without   
   an index) only denotes the data type, not a data value.   
   >   
   > "xt" is a number on the stack no different from "u" "n" "char" "flag" other   
   > than in what it denotes.   
   >   
   > Why differentiate the others when they differ in value but not "xt" ?   
      
   I don't mean that "xt" is special among the data types. It's just an   
   example. My point is about the stack notation in general (as a system of   
   symbols) [1].   
      
   In the stack notation, the diagrams "( foo -- foo )" and "( foo1 -- foo2   
   )", where "foo" is a data type symbol [2], are semantically equivalent.   
      
      
      
   [1] Forth-2012, 2.2.2 Stack notation   
      
   [2] Forth-2012, 3.1 Data types   
      
      
      
   --   
   Ruvim   
      
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