Re: [DOC] About Lisp Data Types

[Emanuel Berg]

Kevin Vigouroux via Users list for the GNU Emacs text editor wrote:

> I agree with you. Unfortunately, some parts of the
> explanation are unclear or missing.
>
>     In other languages, an expression is text; it has no
>     other form.

Actually I agree this isn't clear, in C there are for example
expressions that can be simplified to a single value by the
human and also evaluated to that value by the compiler. So on
the contrary arguably it has several "forms" within its
textualness but also in terms of before/after evaluation.

Also "In other languages" is very inexact, what languages are
those if I may? Because there are so many languages that does
anything and everything in so many different ways.

>     In Lisp, an expression is primarily a Lisp object and
>     only secondarily the text that is the object’s read
>     syntax.

Why primarily one thing and "only secondarily" something else?
If it is both, isn't it one thing as much as the other?

Also, isn't it just source and syntax - in Lisp, parenthesized
lists AKA s-expressions - that evaluates to Lisp objects -
that in turn can be expressed as, and evaluates to, source and
syntax, i.e. parenthesized lists AKA s-expressions?

Isn't the object just the run time instance of static source,
an s-expression, that has been evaluated during the execution
of the program?

> Often there is no need to emphasize this distinction, but
> you must keep it in the back of your mind, or you will
> occasionally be very confused.

Better to provide clear definitions:

  1. s-expression = ...
  2. Lisp object = ...
  3. read syntax = ...

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