I'm half way through <@U4UGS5FC7>'s presentation t...

# arrow

[tim]

I'm half way through @raulraja's presentation to the Chicago Kotlin group and was curious when some of these features are available? Eg, from what I can tell @Coercion is not available now is it, if it is which package can I find it in?

[raulraja]

These features will become available as soon as Kotlin 1.4 IR backend is stable in the compiler with plugins, so probably soon, There is an issue @Rachelis tracking. Then we we will perform our first release of Arrow Meta.

For the time being you can try it out cloning https://github.com/arrow-kt/arrow-meta and running /.gradlew publishAndRunIde then load this project or other similarly configured https://github.com/arrow-kt/arrow-typeproofs

[tim]

brilliant 🙏

[raulraja]

The IDE part is being finished now but should be mostly there before they release 1.4 in the compiler

[raulraja]

I mean messages, intentions, looks etc.

[tim]

Thanks for the info. As its not too far in the distant future I'll hold out for the moment as I'm still learning the basics 🙂

[raulraja]

There is many tests with examples too in the meta repo inside compiler plugin module that show all the features with simple examples

[Jörg Winter]

The answer about availability (or cloning arrow-meta + publishAndRunIde) is the same, regarding your presentation of the "inline classes on steroids" presentation (great stuff!) recently at Kotliners, right ?
(I am refferring to the Refinement-Types examples for TextRazor types)
So the only way to try these are as you described above ?

[raulraja]

at the moment yes, you can try them out with snapshots versions of the plugin etc but it’s easier to clone and run to see latest in master. Once 1.4 is ready then we will announce the first stable release for meta

[Jörg Winter]

The Refinement examples work fine using these repos. One question though: these types are strictly compiletime-, not runtime-validated, or ?
Giving at runtime an invalid twitter handle to the refined type (ctor TwitterHandle), does not trigger any validation/fault it seems (?)

[raulraja]

It should validate that unless it’s a bug

[raulraja]

runtime values are enforced to go through the TwitterHandle.from(handle) function

[raulraja]

which returns null if it’s invalid

[raulraja]

there are other functions for validation in the companion including the evaluated rules

[Jörg Winter]

I see, I was using the exposed public constructor of the inline class, guess that is a loophole then ?

[Jörg Winter]

@raulraja ..or put another way: can the constructor be hidden in any way, like making it private or internal ?

[Jörg Winter]

@raulraja any perspective on these inline classes constructors ?

[Jörg Winter]

(I mean, them being public, so there is a way aroung validating, or I am missing something..)

[raulraja]

yes, technically there is a bug where even if you keep it public it won’t let you instantiate it validating the constrains

[raulraja]

but in whatever case you can make the constructor private

[raulraja]

by supressing the warning

[raulraja]

"NON_PUBLIC_PRIMARY_CONSTRUCTOR_OF_INLINE_CLASS"

[Jörg Winter]

ok, this seems to work as expected

@Suppress("NON_PUBLIC_PRIMARY_CONSTRUCTOR_OF_INLINE_CLASS")
inline class TwitterHandle private constructor(val handle: String) { ...

...almost like "beat that, Haskell newtype" 🙂
but then again, Haskell has phantom types too
and then again... I'll have to look into arrow's Const type for similar purposes

[Jörg Winter]

Arrow: almost like learning another language 😉