Re: Several beginner-questions

[Pascal J. Bourguignon]

Lowell Gilbert <lgusenet@be-well.ilk.org> writes:

> "Pascal J. Bourguignon" <pjb@informatimago.com> writes:
>
>> Lowell Gilbert <lgusenet@be-well.ilk.org> writes:
>>> It's certainly possible to write functional programs in Emacs Lisp, just
>>> as in any other Lisp.  But any program that uses side effects (changing
>>> a buffer being one obvious example) is not a functional program.
>>
>> And what do you do of the buffer monad?
>
> I don't understand the question.  

Purely functionnal programming languages use some kind of monad to
implement state mutation.  If you wrote an emacs in Haskell, you
conceivably would have a buffer monad so that you can insert strings and
and move point in a buffer.  There is strictly no difference with emacs
lisp, where you can insert string and move point in a buffer.  Emacs
lisp implements the buffer monad that Haskell programmers would implement
to write an emacs.

So the meaning of my question is that you cannot critize a program that
uses side effects changing a buffer for not being a functional program,
because a program in a purely functionnal programming language would do
exactly the same, by implementing a buffer monad.


-- 
__Pascal Bourguignon__                     http://www.informatimago.com/
A bad day in () is better than a good day in {}.