Re: lexicographic list comparison

[<tomas@tuxteam.de>]

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On Sat, Sep 10, 2022 at 11:07:49AM +0200, Mattias Engdegård wrote:
> 9 sep. 2022 kl. 21.27 skrev Sam Steingold <sds@gnu.org>:
> 
> > What do you do when sorting a list of lists of numbers?
> 
> Sigh deeply and write ad-hoc code for the nth time.

:-)

> It would be useful to have a total ordering on Lisp values: for heterogeneous ordered collections, for simplifying multi-key sorting, for normalising unordered collections, etc.
> 
> The devil is in the details: are strings compared with our without properties? Do we observe the wonky IEEE rules for ordering floats? Is there a particularly useful ordering between elements of different types? Do we need to worry about circularity? How do we compare hash tables? And so on.
> 

And language-dependent collation, and Unicode equivalence, and NaNs
and...

Details, indeed :-)

A look at the troubles and tribulations a DBMS goes through gives one
a rough idea on how interesting a general solution can become...

> Consistency with `equal` would be desirable (up to hash table identity, perhaps).

This, too :)

Cheers
-- 
t

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