Hi, I'm thinking about writing a compiler plugin t...

# arrow-meta

[trathschlag]

Hi, I'm thinking about writing a compiler plugin to support named parameters in function types.

I need it to do the following transformation:

@NamedParameters
typealias UpdateUserByToken = (userToken: String, update: (User) -> User) -> Unit

to

interface UpdateUserByToken {
    operator fun invoke(userToken: String, update: (User) -> User): Unit

    companion object {
        operator fun invoke(impl: (userToken: String, update: (User) -> User) -> Unit) = object: UpdateUserByToken {
            override fun invoke(userToken: String, update: (User) -> User) = impl(userToken, update)
        }
    }
}

So you can stuff like this:

val updateUserByToken = UpdateUserByToken { userToken, update ->
    // implement
}

[...]

updateUserByToken(userToken = "1234") {
    user.copy(email = "<mailto:[e-mail]|[e-mail]>")
}

Is this possibly with arrow-meta? How could I distribute this plugin to my colleagues? Thanks in advance!

[shikasd]

I am probably missing something, but named parameters are already supported in lambda types?

[trathschlag]

Not on the calling site:

updateUserByToken(userToken = "1234") {
    user.copy(email = "<mailto:[e-mail]|[e-mail]>")
}

does not work currently

[trathschlag]

message has been deleted

[trathschlag]

Another benefit/drawback would be that these interface based functional types are typed by name instead of signature

[shikasd]

Ah, got it.
You certainly can transform the code either by using quote transforms or generating the bytecode / descriptors yourself.
See hello world example with transform here: https://github.com/arrow-kt/arrow-meta/blob/master/compiler-plugin/src/main/kotlin/arrow/meta/plugins/helloWorld/DummyPlugin.kt