🚀 go-pugleaf

In article <415@data.UUCP> kend@data.UUCP (Ken Dickey) writes:
> There are a number of programming languages, Scheme and ML among them,
> which do not have a pointer abstraction.

The *only* abstractions in scheme are a pair of pointers or a value.

> [After programming in Scheme for a few days, no
> one ever "falls off the end of a pointer chain" or "defererences a
> bogus pointer"].

Sure. If you've got data in a list, say:

	("da Silva" "Peter" "ferranti.com" "peter")

And you accidentally return (cdr list) instead of list, you have all the
problems as you do in C when you return a pointer to the middle of the
array. Oh, sure, the *symptoms* are different, but when you have an
object (a C pointer, or a dotted pair) that can point to any arbitrary
place in any non-atomic language object (a string, or a list) you have the
exact same problem.

This is not to say that scheme doesn't make the consequences of falling
off a list or taking the cdr of a bogus pair less dire, but claiming
that languages like scheme "don't have a pointer abstraction" is going
a bit far.
-- 
Peter da Silva.   `-_-'
+1 713 274 5180.   'U`
peter@ferranti.com