On Thu, Feb 15, 2018 at 9:41 PM, Larry McVoy <lm@mcvoy.com> wrote:

On Thu, Feb 15, 2018 at 09:38:02PM -0500, Dan Cross wrote:
> On Thu, Feb 15, 2018 at 8:56 PM, Lawrence Stewart <stewart@serissa.com>
> wrote:
>
> > ITA???s airline flight booking system, that was used by Orbitz and others
> > was pretty much entirely written in Common LISP, and it was certainly both
> > large and commercially successful. Orbitz was bought by Google for $700
> > million. I don???t know how much of the LISP survived sustained attention by
> > Google.
> >
>
> Google bought ITA, not Orbitz. Most of the logic in QPX is still in Common
> Lisp, but it's not what you'd call "idiomatic" CL code. If one reads a
> bunch of Paul Graham and Peter Norvig books and then gets onto QPX with the
> expectation of that sort of elegance, you end up pretty unhappy pretty
> quick. They do a lot of things very differently to squeeze as much
> performance as they can out of what has, historically speaking, been a
> fairly mediocre compiler.

Which is sort of my point. I don't know all the details but lisp and
performance is not a thing.

That's a tad unfair.

It *can* be fast, it's just that the "Lisp" you're writing in that case probably isn't the Lisp you wanted to be writing when you read about how cool and elegant Lisp was: you're avoiding some constructs to prevent boxing and unboxing arguments (e.g., put things inside of labels or flet's instead of defun's or passing arbitrary lambdas around) or generating useless garbage (don't cons up a list; setq the cdr) and favoring others that are less elegant to get better object code out of the compiler.

If you can stomach the death-defying twists and turns from all the hoops you have to jump through for all of that nonsense, then you can make it fast -- but at the loss of the expressive advantage. But that trade-off begs the question: why not write in a language that lets you write fast (executing) code without jumping through hoops? That's a fair thing to ask and most of the answers in Lisp's favor aren't particularly great.

- Dan C.