There's not too many times you get a chance to make a second first impression.

[paganaye]

I follow the instruction on the readme.md at this address
https://github.com/arrow-kt/arrow-meta-examples

git clone https://github.com/arrow-kt/arrow-meta-examples

Cloning into 'arrow-meta-examples'...
remote: Enumerating objects: 684, done.
remote: Counting objects: 100% (162/162), done.
remote: Compressing objects: 100% (69/69), done.
remote: Total 684 (delta 107), reused 105 (delta 79), pack-reused 522
Receiving objects: 100% (684/684), 162.92 KiB | 156.00 KiB/s, done.
Resolving deltas: 100% (238/238), done.

so far so good.
Then
cd arrow-meta-examples/

(base) pascal@pascal-MS-7B79:~/code/github/arrow-meta-examples$ cd demos/
(base) pascal@pascal-MS-7B79:~/code/github/arrow-meta-examples/demos$ ./gradlew clean build
Downloading https://services.gradle.org/distributions/gradle-6.8.3-bin.zip
......................................................................................................

Welcome to Gradle 6.8.3!

Here are the highlights of this release:
 - Faster Kotlin DSL script compilation
 - Vendor selection for Java toolchains
 - Convenient execution of tasks in composite builds
 - Consistent dependency resolution

For more details see https://docs.gradle.org/6.8.3/release-notes.html

Starting a Gradle Daemon (subsequent builds will be faster)

> Configure project :optics-compiler-plugin-demo
Applying arrow-optics-plugin for optics-compiler-plugin-demo ...

> Configure project :refined-types-compiler-plugin-demo
Applying arrow-refined-types-plugin for refined-types-compiler-plugin-demo ...

> Task :optics-compiler-plugin-demo:compileKotlin
w: /home/pascal/code/github/arrow-meta-examples/demos/optics-compiler-plugin-demo/src/main/kotlin/io/arrowkt/example/Context.kt: (15, 14): Condition 'i != null' is always 'true'

> Task :optics-compiler-plugin-demo:test

LensTest > Lenses will be generated for data class() PASSED

> Task :refined-types-compiler-plugin-demo:compileKotlin FAILED
e: -1 should be > 0, -1 should be even : io.arrowkt.example.PositiveIntEven.Companion.invoke

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':refined-types-compiler-plugin-demo:compileKotlin'.
> Compilation error. See log for more details

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 1m 13s
12 actionable tasks: 8 executed, 4 up-to-date
(base) pascal@pascal-MS-7B79:~/code/github/arrow-meta-examples/demos$ 

I am just discovering your repository.
It feels that you're right -1 is not even and positive but we expect this to be caught don't we?

[raulraja]

This repo is no longer maintained, I'll archive it. For maintained and active repos in Arrow please take a look at https://arrow-kt.io/ or swing by the kotlin slack #arrow channel