[plt-scheme] Native code generation and immutable pairs

On Mar 11, 2006, at 1:20 AM, Jim Blandy wrote:

> On 3/10/06, Lauri Alanko <la at iki.fi> wrote:
>> Also, at some point eq? on pairs needs to be unspecified. Once pairs
>> have no state, they don't need identity, either.
>
> I like Henry Baker's paper about this:
> http://home.pipeline.com/~hbaker1/ObjectIdentity.html
>
> It bothers me that the more I think about this stuff, the more I
> appreciate ML...

The abstract suggests that what he wrote up in 1990-92 in this essay 
had been well-known in the Scheme and OpSem community. Indeed, I was 
teaching

   (define (my-eq? x y) ... (set-car! x 0) ... (set-car! y 1) ... (= 
(car y) 1) ...)

in the freshmen course at Rice back then. My own knowledge goes back to 
Indiana, probably some Steele-Sussman paper. The op-sem people proved 
things about this eq? as early as 1986 LiCS (Ian Mason, advised by 
Carolyn Talcott).

Computer science, the art of multiple rediscovery.

-- Matthias