fxtest.kt

import arrow.core.Either
import arrow.core.extensions.fx
import arrow.core.flatMap
import java.lang.IllegalStateException

class Hello {
    companion object {
        @JvmStatic
        fun main(args: Array<String>) {
            val count = 100000

            println("count = $count")

            for (i in 1..10) {
                check("when", count) {
                    byWhen { somefunc() }
                }

                check("flatmap", count) {
                    byFlatMap { somefunc() }
                }

                check("fx", count) {
                    byFx { somefunc() }
                }
            }
        }
    }
}

fun check(msg: String, count: Int, f: () -> Unit) {

    val start = System.currentTimeMillis()

    for (i in 1 .. count) {
        f()
    }

    val end = System.currentTimeMillis()

    println("$msg: ${end-start} millisec")
}


fun byWhen(f: () -> Either<Exception, String>): Either<Exception, String> {
    val a = f()

    return when(val a = f()) {
        is Either.Right -> {
            when (val b = f()) {
                is Either.Right ->
                    Either.Right(a.b + b.b)
                else -> Either.Left(IllegalStateException("hoge"))
            }
        }
        else -> Either.Left(IllegalStateException("fuga"))
    }
}

fun byFlatMap(f: () -> Either<Exception, String>): Either<Exception, String> {
    return f().flatMap { a ->
        f().map { b ->
            a + b
        }
    }
}

fun byFx(f: () -> Either<Exception, String>): Either<Exception, String> {
    return Either.fx<Exception, String> {

        val a = f().bind()
        val b = f().bind()

        a + b
    }
}


fun somefunc(): Either<Exception, String> =
    Either.Right("aiueo")

fun somefunc2(): Either<Exception, String> =
    Either.Left(IllegalStateException("fuga"))

count = 100000
when: 76 millisec
flatmap: 92 millisec
fx: 1211 millisec
when: 6 millisec
flatmap: 5 millisec
fx: 586 millisec
when: 8 millisec
flatmap: 5 millisec
fx: 381 millisec
when: 8 millisec
flatmap: 5 millisec
fx: 411 millisec
when: 8 millisec
flatmap: 15 millisec
fx: 473 millisec
when: 10 millisec
flatmap: 8 millisec
fx: 543 millisec
when: 6 millisec
flatmap: 4 millisec
fx: 346 millisec
when: 5 millisec
flatmap: 4 millisec
fx: 366 millisec
when: 10 millisec
flatmap: 9 millisec
fx: 422 millisec
when: 5 millisec
flatmap: 4 millisec
fx: 314 millisec