A question on modification of a list via a function invocation

[Gregory Ewing]

Chris Angelico wrote:
> This is another proof that you can't divide everything into "pass by
> value" vs "pass by reference"

True, but that doesn't mean you should deny that something
is pass-by-value when it actually is.

> In C, a string is not an
> entity; it's simply an array of characters. Arrays are never passed by
> value;

I think it's more accurate to say that arrays are never
passed at all in C.

A better name for pass-by-value would be "pass-by-assignment".
Passing a parameter by value is equivalent to assigning it
to a local name.

> yet everything in C is passed by value. So you pass a
> pointer... by value.

Yes, because that's what happens when you assign an array
in C.

If it seems screwy, it's because assignment is screwy in
C, not parameter passing.

> What would you define LISP's semantics as? Pass by value? Pass by
> reference? Pass by name? Pass by immutability? Pass the salt?

Let's see... the expression being passed gets evaluated
once at the point of call, and the result gets bound to
a local name. Looks exactly like pass-by-value to me.

> unless you mess around with "passing a
> reference by value" or other shenanigans.

What on earth are you talking about? I didn't even use
the words "value" or "reference" in the previous paragraph.

-- 
Greg