Hi,
indeed, transducers provided a way to achieve this, e.g.
#(12 7 'a' nil #(0)) pipe
filter: #notNil;
filter: #isNumber;
map: #squared;
filter: #even;
into: OrderedCollection.
But this feature is deprecated, as it was not that useful. The preferred
way to do this is either:
#(12 7 'a' nil #(0))
transduce: #notNil filter * #isNumber filter * squared map * #even
filter
reduce: Set accumulate.
or:
Set <~ #even filter
<~ #squared map
<~ #isNumber filter
<~ #notNil filter
<~ #(12 7 'a' nil #(0)).
The advantage of the transducer approach is that it decouples
filtering/mapping/etc. from iteration and aggregation. This facilitates
reuse and makes it trivial to provide all operations to new custom data
types.
However, I didn't have time to finish the Pharo port of Transducers, yet.
Hence, the a current version is available in Cincom's Public Store or
(most current) directly from me only. But if you are interested and have a
nice use case, I'd be happy to help out.
Best, Steffen
Am .10.2018, 08:45 Uhr, schrieb Julien <julien.delplan...@inria.fr>:
I think this was the idea of Transducers as well.
Julien
---
Julien Delplanque
Doctorant à l’Université de Lille
http://juliendelplanque.be/phd.html
Equipe Rmod, Inria
Bâtiment B 40, Avenue Halley 59650 Villeneuve d'Ascq
Numéro de téléphone: +333 59 35 86 40
Le 17 oct. 2018 à 09:13, Peter Uhnak <i.uh...@gmail.com> a écrit :
Hi,
is there some library that will allow me to chain select:/collect:/...
via cascade?
E.g.
#(12 7 'a' nil #(0)) query reject: #isNil; select: #isNumber; collect:
#squared; select: #even?
The point is to not have to write billion parentheses when building a
more complex query.
I imagine this would be pretty easy to write, but figured I ask first.
Thanks,
Peter
