strangest systems I've sent email from

Eric Christopherson echristopherson at gmail.com
Sun May 22 14:52:29 CDT 2016


On Sun, May 22, 2016, Mouse wrote:
> >> Also, PostScript has a lot of language syntax, whereas FORTH has
> >> immediate words that act like language syntax.  (The difference is
> >> that FORTH makes it possible to change those words, thereby changing
> >> the apparent syntax.)
> > What do you mean by that?
> 
> Consider a simple definition
> 
> : foo swap - ;  ( inverted subtraction )
> /foo { exch sub } def  % inverted subtraction
> 
> (The first is FORTH[%], the second PostScript.)  Each of these has some
> "syntax" bits.  In FORTH, :, ;, (, and ).  In PostScript, the leading
> /, {, }, and %.

Interesting. I thought { } were just plain old words, but I'll at least
concede the rest.

> The difference is that in FORTH, you can create new immediate words
> and/or redefine the existing ones; : can do something other than
> beginning the definition of a word, and you can arrange to begin the
> definition of a word with something other than :.  In PostScript, none
> of this is mutable short of hacking on the underlying implementation
> (and if you do that the result isn't PostScript any longer).
> 
> [%] I think.  I don't really know FORTH; does it use - for subtraction?
> 
> /~\ The ASCII				  Mouse
> \ / Ribbon Campaign
>  X  Against HTML		mouse at rodents-montreal.org
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-- 
        Eric Christopherson


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