BracketUsage.kt

import arrow.effects.IO

class File(url: String) {
    fun open(): File = this
    fun close(): Unit {}
    override fun toString(): String = "This file contains some interesting content!"
}

fun openFile(uri: String): IO<File> = IO { throw RuntimeException() }

fun closeFile(file: File): IO<Unit> = IO { println("File is closed")
    file.close() }

fun fileToString(file: File): IO<String> = IO { file.toString() }

fun main(args: Array<String>) {
//sampleStart
    val safeComputation = openFile("data.json").bracket(
        release = { file -> closeFile(file) },
        use = { file -> fileToString(file) })
//sampleEnd
    println(safeComputation.unsafeRunAsync { result ->
        result.fold( {println("Error: $it")}, { println("Result: $it")})
    })
}