I'm playing with Arrow Analysis (AA). It seems like `require` is treated differently by the compiler...

# arrow

[julian]

I'm playing with Arrow Analysis (AA).
It seems like require is treated differently by the compiler compared with a project that doesn't use AA. Is this a correct observation?
For example, this, which doesn't explicitly use any AA features,

fun fn() {
    val x = 1
    require(x == 1)
}

results in a compiler error: could not parse predicate: x == 1
Whereas in a project without AA, there's no compiler error.

[Alejandro Serrano Mena]

yes, this is right: AA treats the require blocks as preconditions on the arguments, so they must follow a specific pattern (be first, only mention argument names)

[Alejandro Serrano Mena]

you can leave it here, but you'll get a warning about a predicate which cannot be treated by AA

[julian]

Thanks @Alejandro Serrano Mena!

[Richard Gomez]

Would it be possible to provide a clearer error message, or does could not parse predicate get returned for a variety of circumstances?

I am a mere mortal and probably wouldn't be able to figure out what that error/warning refers to.

[Alejandro Serrano Mena]

of course, developer UI is key for a tool like AA to be useful. I've just created a ticket in the repo to track this https://github.com/arrow-kt/arrow-analysis/issues/23