Re: Srfi-159/166 - monadic formatting for guile

[John Cowan <cowan@ccil.org>]

On Sun, Jun 16, 2019 at 2:47 AM Mark H Weaver <mhw@netris.org> wrote:


> How do you implement 'written-shared', 'pretty-shared', and
> 'trimmed/lazy'?  In particular, how do you avoid non-termination when
> asked to print cyclic data, when the cycle includes a non-standard data
> type printed using a custom printer?  For example, what if you print a
> list that includes an object whose custom printer will print output that
> includes the same list that you started with?
>

Of course it can't cope with that.  But consider an object whose custom
printer outputs its instance variables where one of those instance variables
has been assigned to the object itself.  No procedure other than the object
printer itself is going to be able to break *that* loop.


John Cowan          http://vrici.lojban.org/~cowan        cowan@ccil.org
Yes, chili in the eye is bad, but so is your ear.  However, I would
suggest you wash your hands thoroughly before going to the toilet.
        --gadicath