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From: trolfs@vax1.tcd.ie (Tommy)
Newsgroups: comp.lang.forth
Subject: Making Forth easier to swallow.
Message-ID: <44212@vax1.tcd.ie>
Date: 30 May 89 11:10:31 GMT
Organization: Computer Laboratory, Trinity College Dublin
Lines: 65

Request:
      I was told that there was a 5 part version of Forth for the Mac posted
      awhile back (not pocketForth).
      Could someone let me know if they have it? Please? 

Question:

      I was very taken by the articles in Forth Dimensions (XI/1) on extra
      stacks for Forth and local variables. I'd never really thought about
      using extra stacks and even less about local variables, so it was a
      real eye opener. Actually, this was my first time getting Forth
      Dimensions and it gives you some idea of how isolated I am.
      I know that this topic must have been discussed to death before, but
      I'm very interested to hear what you (The Netforthers) have to say
      about using extra stacks and local variables.

      One of the things discussed was the freeing of the Return stack from
      holding anything other than return addresses. This idea appeals to me
      as I always feel uneasy about storing things there. What really
      interests me though is, if more stacks are needed (and I think they
      are), what is the minimum number and how can they be best used? (ie,
      is a floating point stack good programming or - for uniformity - should
      all parameters be passed only on the parameter stack?) 

      Another thought is the use of local variables. Are more people looking
      to local variables for easier coding and better readability? And if 
      done well, couldn't local variables make for faster run-time code?
      Probably, if you had complicated stack manipulations. But even if they
      don't, their readability would make Forth a LOT more palatable to
      non-Forth programmers (which would help Forth's image no end).
      I for one think that Forth's parameter passing and manipulation and also
      it's stack configuration, should to be built on and expanded if it is to
      be considered a 'serious' alternative to present day compiled languages. 

      Well, that's what I think (:-). It would be nice know what the experienced
      Forth programmers on the Net think. Are more stacks needed? Where can they
      benefit best? Are local variables overall useful or do they take away
      from the Forth philosophy of "Simple is beautiful"? (Though, I thought
      John Hayes's implementation, in FD p18, looks very simple and improves 
      readability greatly, where as some of the other implementations didn't.)
      But, the main question that I'm interested in is "Are extra stacks and
      local variables going to be made standard?". 
      Then again, maybe it's the Forth novices who are in a better position 
      to know what is needed to make Forth an easier pill to swallow. After 
      all, they (we) still have the bitter after taste.

 
Here is a very simple example of John Hayes's local variables:

   : add  ( a b -- a+b )
     {                    / { mark start of new scope  
        local b           / local creates the local variable b and
        local a             /     pops the top of stack is in to it    
        
        a b +
     }                    / } releases local variables
    ;


-- 

Tommy                                                               $P-)
                                              E-mail: trolfs@vax1.tcd.ie 
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