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 Content preview:  Hi all, On 26.12.17 16:56, Sebastian Bergmann wrote: > Am
   26.12.2017 um 16:46 schrieb lists@rhsoft.net: >> would you mind to explain
    this? > > "Foo|Bar", "array|string", etc. (still) make no sense to me. >
   > "scalar" makes sense to me although it is but an alias for > "bool|float|int|string".
    [...] 
 
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Subject: Re: [PHP-DEV] [RFC] [DISCUSSION] Scalar Pseudo-type
From: markus@fischer.name (Markus Fischer)

Hi all,

On 26.12.17 16:56, Sebastian Bergmann wrote:
> Am 26.12.2017 um 16:46 schrieb lists@rhsoft.net:
>> would you mind to explain this?
> 
> "Foo|Bar", "array|string", etc. (still) make no sense to me.
> 
> "scalar" makes sense to me although it is but an alias for
> "bool|float|int|string".

I followed the discussion and found it interesting how strong the focus 
shifted about the discussion of the practical use cases. I would be for 
union types or scalars in ab instant, but I never had reason to scan our 
code-base and figure what would make really sense.

Mind you this is a private codebase (Laravel based, as can be seen by 
some of the class names) but one where we tend to be very explicit about 
documenting everything, thus I knew I could just go ahead and extract 
the type hints using the '|' character and get back a pretty complete 
picture:

$ grep -r '@param' *|grep \| | awk '{ print $4 }'|sort -u
Attachment[]|Collection
Attachment[]|null
Builder|null
Channel|Post|int|null
Channel|int|null
ClientInterface|null
Client|int|null
Collection|Attachment[]
Collection|Channel[]
Collection|Comment[]
Collection|JsonapiModel[]
Collection|Model[]
Collection|Post[]
DateTime|Carbon|string|null
Dispatcher|null
EloquentCollection|JsonapiModel[]
Exception|null
Group|Group[]|Client|Client[]|Channel|Channel[]|null
Group|int|null
JsonapiModel|null
Model|int|null
Post[]|null
Post|int|null
Profile|int|null
ResponseInterface|null
Throwable|null
User|int|null
\ArrayAccess|array|JsonapiModel[]|null
array|false
array|null
int[]|int
int|int[]
int|null
mixed|null
null|LoggerInterface
null|Model
null|Model[]|Collection
null|string
string[]|Expression[]
string|int
string|null

This is extracted from a codebase with ~400 files and ~43k LOC (incl. 
comments). I'm not saying anything like this is relevant codebase, but 
it's a project whose code quality I know well and I know the reason for 
every piece there.

Since the discussion focuses on scalars here and ignoring all the 
nullables (they're auto-documented that way via PhpStorm) as well as 
ignoring the pseudo array-type hints, this leaves us really with only:

- array|false
   Only 1 occurrence, used for crafting a remote HTTP call which has an 
interface which accepts either an array or false ?‍♀️
- string|int
   Only 1 occurrence, used for error codes which may come in either 
flavor, send back via HTTP somewhere

I was surprised how less of a use we would really have for a) `scalar` 
itself and b) scalar unions.

OTOH, typed array hints seem to be very useful as are class based union 
types. Although if one looks closely, it's clear this isn't a "union" 
problem, but rather an emulation due to the absence of Generics, e.g.

Attachment[]|Collection

Is clearly a replacement for something like

Collection<Attachment>

I hope I didn't distract to much from the discussion but though I throw 
in some data from an actual application. I'm sure there are much better 
OSS projects out there which could be used for such analysis.

thanks,
- Markus