>
> Try
>
> GETDATABASE('AbelianMonoid, 'CONSTRUCTORCATEGORY)$Lisp and
> GETDATABASE('DistributionCategory, 'CONSTRUCTORCATEGORY)$Lisp
>
> While in the first case we have in the returns expression
>
> (SIGNATURE (Zero) ($) constant)
>
> the second call yields
>
> (SIGNATURE (Zero) ($))
>
> without the "constant" marker.
>
> AbelianMonoid defines
>
> 0 : constant -> %
>
> while DistributionCategory defines
>
> 0 : () -> %
>
> I consider "constant -> %" as a funny writing for "%", the mapping
> () -> % is clearly not the same type as %. Mathematically, yes, there's
> no difference, but ()->% can have side effects in SPAD, while % can not.
>
> It probably currently makes no difference in FriCAS, but I would rather
> like to write
>
> 0: %
>
> into the .spad file instead of "constant -> %" or "() -> %".
>
> Furthermore since the type ()->% is for me not equivalent to %, I
> consider it even a bug.
>
> Distribution(R) implements 0 via
>
> 0 == distributionByMoments sequence repeating [0]
>
> but we have
>
> distributionByMoments : Sequence R -> %
>
> so the result type is clearly % and not ()->%.
>
> Waldek, can we get rid of "constant->" and "()->" for the definition of
> constants already now? I think you've worked on this, but I'm not sure
> about the status.
Appropriate change was commited in January 2012. You need to
check if it works as you want (IIRC you wanted additional
change to the interpreter).
--
Waldek Hebisch
[email protected]
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