mailing-list for TeXmacs Users

[Karl Hegbloom <address@hidden>]

On Mon, 2004-10-18 at 14:07 +0200, Javier Arántegui wrote:
>
> During this weekend one question raised, why TeXmacs uses so much Scheme. I 
> don't think it's the most popular language. Maybe it's the best suited for 
> the job. It's just curiosity.

Scheme is actually quite popular in the academic community.  Here are
some links you may find useful.  There are two free textbooks:

 http://mitpress.mit.edu/sicp/
 http://www.htdp.org/
 http://www.teach-scheme.org/

The structure of the Scheme language closely resembles that of SGML/XML,
and Scheme is used for DSSSL:

 http://www.jclark.com/dsssl/

The Emacs text editor contains a Lisp dialect that is similar in some
ways to Scheme.  Scheme is a simpler and more modern dialect of Lisp.
Emacs Lisp symbols have both a function and value slot - in other words,
there are two namespaces.  Scheme symbols have only a value slot, and
that value can be of type 'function'.  I think this is considered
cleaner design.  Emacs Lisp is dynamically scoped, where a variable's
value is visible to called functions, but Scheme is lexically scoped.
Here's what that means:

(define somevar "global value")

 (...
   (let ((somevar "a value"))
     (somefunction "a string passed to it"))
   ...)

In Emacs Lisp, the value of 'somevar' as seen by 'somefunction' is "a
value", but in Scheme, it would see the "global value".  Lexical scoping
is more in keeping with the principal of least surprise.  What you see
in a function is what it sees at run-time.

Many people really love the Emacs editor.  Quite a few users will
actually write a little bit of Lisp for it, to customize or extend it's
functionality.  The Lisp languages are powerful, easy to learn, to
extend, and to read.  Much of the Lore of Computer Science is embodied
in the Lore of Lisp.

These reasons are most likely why Scheme was chosen for TeXmacs.

-- 
    Karl Hegbloom
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