Re: [stack] What does "concatenative" actually mean?

John Nowak wrote:
> The object systems in Factor and Forth do break referential  
> transparency. If this means that are not "purely concatenative"  
> depends on who you ask.

Thanks for taking the time to explain; I agree with most of what you've
said, but this is false.

Forth doesn't have any "the object system"; some of the open-source
alternatives available do destroy local concatenativity, but most of
them don't.

Factor's official object system is definitely fully concatenative. It
won't matter who you ask; if they disagree with me, they're wrong. ;-)

Technical point: Referential Transparency in a concatenative language is
different from the same concept in an applicative language. In one
sense, it's harder to use, since you can't simply move words from one
place to another (without rearranging the stack); in another sense it's
easier to use, since you can "factor out" a word without having to do
any work at all (cut and paste is sufficient). Unlike applicative
languages, you do NOT have to worry about functional state; the fact
that the stack acts as a monad means that the state is already
preserved; even I/O can be modelled properly.

> - John

-Wm