Home Original page

Why is Python popular, while Lisp and Scheme aren't?

John Baxter jwbaxter at spamcop.net
Mon Nov 11 11:53:28 EST 2002 
In article <7h3lm402zq5.fsf at pc150.maths.bris.ac.uk>,
 Michael Hudson <mwh at python.net> wrote:

> Carl Banks <imbosol at vt.edu> writes:
> 
> > Dennis Lee Bieber wrote:
> > >        As I recall, they also derive from the hardware that LISP was 
> > >        first 
> > > implemented on -- C)ontents A)ddress R)egister, and C)ontents D)ata 
> > > R)egister (or some variation thereof). Something to the effect that the 
> > > original machine storage unit (words) effectively held two pointers, 
> > > accessed as address and data...
> > 
> > 
> > Which is kind of funny.  You'd expect the Data Register to point to
> > the nth item in the list, and Address Register to point to the next
> > cons cell.  But the reverse is true.
> 
> I think the d in cdr stands (stood) for decrement, not data.  But the
> web seems confused on the issue.  It just means "second half of cons
> cell" to me...

It was "decrement" in IBM's view of the machine, and in the usage of 
those instructions which had the field.

  --John
More information about the Python-list mailing list