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Re: Attila Forth compiler

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on 29/01/2015 22:54:37, "WJ" wrote:
> Gerry Jackson wrote:
> 
> 
>> I stumbled across the web-site below.
>> Searching comp.lang.forth on Google Groups
>> for Attila found nothing so people may not
>> be aware of this system and may find it of
>> interest.
>>
>>
>> http://www.threaded-interpreter.org/manual/book/attila.html
> 
> 
> 
> Attila Forth seems much more powerful than ANS Forth.

What makes you think that? Did you read the document? It states "It
adheres closely to the Forth language standard promulgated by ANSI."

> 
> 
> MAP( xt elem -- )
> 
> Destructively map the word xt over the elements of the list
> from elem, replacing each element with the result of executing
> xt with the previous value on the top of the stack.
> 

These are just words the author of Attila has provided to operate on
doubly-linked lists. They are not inherent to the language.
http://www.threaded-interpreter.org/manual/book/sec_words_lists.html

Here's an ANS Forth version of a list iteration:

: iterate   ( i*x node iterator -- i*x' ) 
\ iterate over a linked list of nodes
            >r                                 
            begin ?dup
            while
              r@ over @
              >r execute r>                    
            repeat r> drop ;

ITERATE is more generic and more useful than MAP, in that it allows a
wider range of results than just replacing each element as in MAPs case.
ITERATE can be used to build Attila's FOLDR and FOLDL and a wide range of
other "higher order list operations".

(As an aside, I'd argue that the author has got the operands MAP ( xt
elem -- ) the wrong way round; you're more likely to be operating with
elem on the top of the stack before wanting a MAP, so requiring a SWAP to
get the XT in the right place.)

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Attila Forth compiler Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-01-29 20:27 +0000
  Re: Attila Forth compiler "WJ" <w_a_x_man@yahoo.com> - 2015-01-29 22:54 +0000
    Re: Attila Forth compiler "Alex McDonald" <blog@rivadpm.com> - 2015-01-30 15:36 +0000
      Re: Attila Forth compiler "Alex McDonald" <blog@rivadpm.com> - 2015-01-30 15:40 +0000
  Re: Attila Forth compiler anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-01-30 15:56 +0000
    Re: Attila Forth compiler Richard Owlett <rowlett@cloud85.net> - 2015-01-30 11:09 -0600
    Re: Attila Forth compiler "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-01-31 02:58 -0500
      Re: Attila Forth compiler anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-01-31 11:48 +0000
  Re: Attila Forth compiler visualforth@rocketmail.com - 2015-01-30 08:42 -0800
    Re: Attila Forth compiler "Alex McDonald" <blog@rivadpm.com> - 2015-01-30 17:16 +0000
    Re: Attila Forth compiler Richard Owlett <rowlett@cloud85.net> - 2015-01-30 11:19 -0600
  Re: Attila Forth compiler Christopher Douglas <christopherdouglas35@gmail.com> - 2015-01-31 06:29 -0800

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