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Date: Mon, 28 Mar 2016 11:43:59 +0530
Message-ID: <CAHvhOfjdOR7Obf4BHcN7aXbUnpkMEBh1m3cH=Eq5R66PeeuN1g@mail.gmail.com>
To: Facundo Martinez Correa <fnmartinez88@gmail.com>
Cc: PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] RFC Proposal: Maybe monad and execution time
 polymorphic methods
From: kelerest123@gmail.com (Kubo2)

Hi Facundo Mart=C3=ADnez,

I think the best solution to yourself described problem above would be
the Null Object Design Pattern
(https://en.wikipedia.org/wiki/Null_Object_pattern). In my opinion,
NULL belongs to PHP and this language never aimed to become Java or
similar.

Jakub

On 22 March 2016 at 01:34, Facundo Martinez Correa
<fnmartinez88@gmail.com> wrote:
> Hello,
>
> I am reaching you in order to obtain feedback on this RFC proposal.
>
> I have been playing with PHP 7 for a project in the company that I am
> currently working for. One of the many drawbacks that I saw in PHP was th=
e
> there were no types. With type hinting I had confindence again in PHP. Wi=
th
> return type hinting a wasn't able to resist to try it. So here I am, maki=
ng
> a whole new platform entirely in PHP 7, using type hints in everything.
> Arguments and returns alike. Given my tendency to language purity imagine
> my surprise when my code inadvertently tryied to sneak a NULL into a meth=
od
> expecting an object... And failing thanks to strictness in object and nul=
l
> treatments in the new PHP 7. "SWEET!" I yelled.
>
> Now imagine my dumbfoundedness when a Repository of mine tryed to return =
a
> NULL, and because it ought to return have returned a User, it threw a
> TypeError. At first I said "sweet." But then I realized the problem. Ther=
e
> are many times where we need uncertainty. Code is a reflection of reality=
,
> and as such, it must reflect uncertainty. NULL is a good enough way to
> express nonexistence, albeit a bad one. We have been using it in code for
> years, but it is also used to say many things. Things that cause
> uncertainty in the code. I receive a null, does it mean it doesn't exists=
?
> That it will exist? Should I allow it? Is it a good value? I for sure don=
't
> know. And in my experience, I have used it for many of those cases. And i=
n
> many situations that I'm not proud of, all of them at the same time.
>
> So I want to "return a NULL". I want to express uncertainty, a
> nonexistence. But I want to express that I will return something. And I
> want to have this NULL checking at interpretation time. I want everything=
,
> and none of the drawbacks. As we say here in Argentina, I want the bread
> and the cake. What can we do to have it? After a bit of thought the Maybe
> monad came to me.
>
> My experience in Haskell reminded me of this. To have a structure than
> represents uncertainty, is the best way to take away the responsibility
> from NULL. To express it in no other way. But my experience in Java has
> taught me that Optional of something is not a good way to tackle the
> problem. I still have to check if my Optional isEmpty. I still have to
> check for null. That is because Java has that type erasure after
> compilation time that doesn't allow me to play nice with polymorphism. Bu=
t
> maybe PHP can. Maybe PHP will give me the polymorphism at execution time =
to
> discern an empty Maybe from the one that is not. So I don't have to check
> for null ever again in my life. So my code can be free of nulls. So I can
> express uncertainty and nonexistance, while I return a User from my
> repository.
>
> I hope someone would like this idea. I'm also open to suggestions.
> Kind regards
> Facundo Mart=C3=ADnez



--=20
Cheers,
Kubis