MEM, DEL, & Co.

[Jonathan Rees <Rees at YALE>]

Looks fun.  Some points:

I don't understand the use of "->" at all.  To me, FIND->TAIL would be a
routine which takes a FIND as its argument, and coerces it somehow to be
a TAIL.  To give it this new meaning (and I couldn't figure out how that
meaning is much different from "-") seems a very bad overloading to me.

I don't see how FIND->TAIL or FIND->SEL generalize, as you say they do, to
the case of N lists.  Which of the N tails or values do you choose to return?

These should probably become generic routines on sequences, not just
lists.  Thus CAR and CDR become HEAD and TAIL, etc.  But this has some
efficiency problems.

Efficiency questions should be addressed somehow; clearly you wouldn't
want to use the code you gave directly, at least not without extensively
hacking the compiler.  (Of course I wouldn't have expected this in your
proposal; just something to think about.)

I think the reason I've avoided working on this problem is that I wanted to
overcome the efficiency problems first.  This is similar to what I had in mind,
though.