list functions:: car, cdr, car

In the AutoLISP programming language, I would like to know the origination of the list functions named "car", "cdr" and "car". In other words, are these acronyms for something? What does "car" stand for? I know what it does. I'm just curious about where these terms came from.

 

Typo: I meant "cadr" in the previous message. I just want to know the origins of these list functions (car, cdr, and cadr).

 

CAR = Contents of the Address Register
CDR = Contents of the Decrement Register.

CADR = (CAR(CDR LST))

Read about the origins of LISP language.

functions named "car", "cdr" and "car". In other words, are these acronyms for something?
What does "car" stand for? I know what it does. I'm just curious about where these terms
came from.

 

I'm not being 'anti-semantic', here, just curious -
I remembered it slightly differently, then did a google search and came up with
something very slightly different from yours or mine:

I thought it was

CAR = Contents of the Address Register
CDR = Contents of the DecrementED Register

which implied (to me, not knowing any better) the use and re-use of a single
register and the stack...

but according to Steve Russell, who apparently was there, "I wrote the first
implementation of a LISP interpreter on the IBM 704 at MIT in early in 1959. I
hand-compiled John McCarthy's "Universal LISP Function". The 704 family (704,
709, 7090) had "Address" and "Decrement" fields that were 15 bits long in some
of the looping instructions. There were also special load and store instructions
that moved these 15-bit addresses between memory and the index registers ( 3 on
the 704, 7 on the others )

We had devised a representation for list structure that took advantage of these
instructions. Because of an unfortunate temporary lapse of inspiration, we
couldn't think of any other names for the 2 pointers in a list node than
"address" and "decrement", so we called the functions CAR for "Contents of
Address of Register" and CDR for "Contents of Decrement of Register".

After several months and giving a few classes in LISP, we realized that "first"
and "rest" were better names, and we (John McCarthy, I and some of the rest of
the AI Project) tried to get people to use them instead. Alas, it was too late!
We couldn't make it stick at all. So we have CAR and CDR."
<clipped from alt.folklore.computers via google.>

I think it just means 'pointer to beginning of first item in a particular
register' and 'pointer to beginning of the rest'. I'm usually wrong though.

 

Luis,
And also to you. Have a nice weekend.

Regards,
Doug

 

Thanks to all who replied. I found the same results yesterday from a fellow programmer. It makes sense since "address" (car) returns the first element in the list and "decrement" (cdr) returns a list with the first element removed. And "cadr" performs two operations, cdr and car, to return the second element of the list. (The cdr function removes the first element, and the car function returns the first element of the new list.)

 

http://home.planet.nl/~faase009/HaCAR_CDR.html