Barry Margolin  <barmar@alum.mit.edu> wrote:
+---------------
|  Tim Bradshaw <tfb+google@tfeb.org> wrote:
| > > Second, why is it called mapcar? Every other Lisp I've looked at
| > > calls this function map.
| > 
| > It's called MAPCAR because pretty much every other existing Lisp
| > called it MAPCAR too, and the CL designers wanted to cause minimal
| > upheaval to the millions of existing lines of code.
| 
| Which begs the question: why did those earlier Lisps call it MAPCAR?
| 
| I think earlier Lisps had a function called MAP.  So when new mapping 
| functions were added to the language, they were given different names: 
| MAPC, MAPCAR, MAPCAN, MAPCON.
| 
| By the time of Maclisp (the primary inspiration for CL) I think MAP had 
| disappeared...
+---------------

According to <http://pdp-10.trailing-edge.com/mit_emacs_170_teco_1220/
01/info/maclisp-commands.info>, Maclisp still had MAP, but its args
and semantics were those of Common Lisp's MAPL, that is:

- Traversal like MAPLIST
- No accumulation of values; side-effecting only like MAPC
- Returns the first list arg as its value

     > (mapl (lambda (x y z) (print (list x y z)))
	       '(1 2 3 4) '(a b c d e) '(+ - * /)) 

     ((1 2 3 4) (A B C D E) (+ - * /)) 
     ((2 3 4) (B C D E) (- * /)) 
     ((3 4) (C D E) (* /)) 
     ((4) (D E) (/)) 
     (1 2 3 4)
     > 

+---------------
| ...but renaming one of the new functions would have caused 
| compatibility problems.  CL introduced a new MAP function,
| since the name was then available.
+---------------

The above URL says Maclisp had all of MAP, MAPC, MAPCAR, MAPLIST,
MAPCAN, & MAPCON -- all as we know them in CL, except that in CL
MAP got renamed to MAPL and MAP got recycled for the new function.


-Rob

-----
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