class PointFeatureDsl {
    // ...
}

class FeatureCollectionDsl {
    fun point(lat: Double, lng: Double, init: PointFeatureDsl.() -> Unit = {}) {
        // ...
    }

    fun toGeoJson(): FeatureCollection {
        // ...
        return FeatureCollection()
    }
}

fun featureCollection(init: FeatureCollectionDsl.() -> Unit) =
    FeatureCollectionDsl()
        .apply(init)
        .toGeoJson()

fun main(args: Array<String>) {
    featureCollection {
        point(1.1, 1.2)
        point (2.1, 2.2 ){
            // ...
        }
    }
}