Re: Should we be touching goops?

[David Kastrup]

Jean Abou Samra <jean@abou-samra.fr> writes:

> Le 05/06/2022 à 14:36, David Kastrup a écrit :
>> Something like ly:moment-add has fewer implied semantics than + .  Not
>> just for humans (who expect + to be more-or-less commutative and
>> associative even though the latter is only approximately the case with
>> floating point arithmetic) but even for Scheme which extends a two-term
>> definition of + into + with an arbitrary larger amount of summands.
>
> Wouldn't the same concerns apply on the C++ side, though?
> I mean, Moment already implements operator+ etc., and C++
> understands a + b + c as (a.operator+(b)).operator+(c).
> How would the C++ side of things be refactored if a distinction
> between points of time and time spans is introduced?

There is a slight difference in that C++ does not have something like

(- a b c)

where an operator can cover an arbitrary number of terms (and the
compiler chooses to apply it multiple times on its own).  There is also
a difference in that the C++ realm is behind a much taller barrier to
the average (and non-average) user than the Scheme realm is and thus
there is less incentive to accommodate "naïve expectations" to the same
degree.

So I'd say that would be a different discussion.  Not that I'd be
particularly looking forward to it.

-- 
David Kastrup