RE: `read--expression' and `read-minibuffer'

[Drew Adams <drew.adams@oracle.com>]

> > I don't see why you think that what it reads is limited, or
> > could or should be limited, to expressions that can be eval'd.
> 
> Because it is tailored for that use case.  The kind of completion
> it provides for instance assumes the S-exp is an Elisp expression.

Of course it is an Elisp expression.  It does not follow that
the Elisp expression that has been read will then be _evaluated_.

A list such as (2 bookmark-alist) or (forward-char forward-line)
is an Elisp exression, and the function and variable names in
these can be constructed using completion.  Neither list is
one that you would then try to evaluate.

And even for what you might consider a more typical case, such
as expression (previous-single-property-change (point) 'foo),
there is nothing that obliges the expression to be evaluated.

Completion can be used and useful when constructing an Elisp
expression to be read, regardless of whether the expression
that is read will be evaluated, or can be evaluated without
error.

What a Lisp program does with a Lisp expression is up to that
program.  Zillions of actions are possible, other than just
evaluation.