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 mo...@rodents-montreal.org
> / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
--
Eric Christopherson
