Re: es dumps core, aargh...

[Paul Haahr <haahr@jivetech.com>]

> Here is a minimal version of the same problem.  This dumps core:
> 
> ; echo <={@ x{x=@{$*}; $&result $x}}
> 
> why?  check this one first:
> 
> ; echo <={@ x{$&result @{$*}} X}
> %closure(x=X)@ * {$*}
> 
> Now, imagine replacing X by the entire closure, and you have a closure
> containing a reference to itself.  That can never be printed, of
> course.

I never got the story right on circular references in es.  Considering
that that was the reason I gave it a garbage collector as opposed to
simpler memory management -- and spent a fairly long time getting the
root set identification right -- I feel pretty silly.

The right answer might be to do something like a Lisp printer does with
#n= and #n# syntax.  (See *PRINT-CIRCLE* in your favorite Common Lisp
reference for details.)  But that doesn't solve the other problem caused
by pickling objects into parseable program text:  shared state that
becomes unshared upon reparsing.

--p