Python syntax in Lisp and Scheme

[Shriram Krishnamurthi]

"Terry Reedy" <tjreedy at udel.edu> writes:

> Lisp (and possibly other languages I am not familiar with) adds the
> alternative of *not* evaluating arguments but instead passing them as
> unevaluated expressions.  In other words, arguments may be
> *implicitly* quoted.  Since, unlike as in Python, there is no
> alternate syntax to flag the alternate argument protocol, one must, as
> far as I know, memorize/learn the behavior for each function.  The
> syntactic unification masks but does not lessen the semantic
> divergence.  For me, it made learning Lisp (as far as I have gotten)
> more complicated, not less, especially before I  'got' what going on.

I'm sorry -- you appear to be hopelessly confused on this point.  I
can't comment on the dark corners of Common Lisp, but I do know all of
those corners of Scheme.  Scheme is a true call-by-value language.
There are no functions in Scheme whose arguments are not evaluated.
Indeed, neithen a function definition, nor an argument location, has
the freedom to "not evaluate" an argument.  We can reason about this
quite easily: the language provides no such syntactic annotation, and
the evaluator (as you might imagine) does not randomly make such a
choice.  Therefore, it can't happen.

It is possible that you had a horribly confused, and therefore
confusing, Scheme instructor or text.

> Question: Python has the simplicity of one unified assignment
> statement for the binding of names, attributes, slot and slices, and
> multiples thereof.  Some Lisps have the complexity of different
> functions for different types of targets: set, setq, putprop, etc.

Again, you're confused.  SET, SETQ, etc are not primarily binding
operators but rather mutation operators.  The mutation of identifiers
and the mutation of values are fundamentally different concepts.

Shriram