arrow-core/arrow.core.computations/ensureNotNull

ensureNotNull

suspend fun <E, B : Any> EitherEffect<E, *>.ensureNotNull(value: B?, orLeft: () -> E): B

Ensures that value is not null. When the value is not null, then it will be returned as non null and the check value is now smart-checked to non-null. Otherwise, if the value is null then the either binding will short-circuit with orLeft inside of Either.Left.

import arrow.core.computations.either
import arrow.core.computations.ensureNotNull

//sampleStart
suspend fun main() {
  either<String, Int> {
    val x: Int? = 1
    ensureNotNull(x) { "passes" }
    println(x)
    ensureNotNull(null) { "failed" }
  }
//sampleEnd
  .let(::println)
}
// println: "1"
// res: Either.Left("failed")

suspend fun <B : Any> NullableEffect<*>.ensureNotNull(value: B?): B

import arrow.core.computations.nullable
import arrow.core.computations.ensureNotNull

//sampleStart
suspend fun main() {
  nullable<Int> {
    val x: Int? = 1
    ensureNotNull(x)
    println(x)
    ensureNotNull(null)
  }
//sampleEnd
  .let(::println)
}
// println: "1"
// res: null

suspend fun <B : Any> OptionEffect<*>.ensureNotNull(value: B?): B

import arrow.core.computations.option
import arrow.core.computations.ensureNotNull

//sampleStart
suspend fun main() {
  option<Int> {
    val x: Int? = 1
    ensureNotNull(x)
    println(x)
    ensureNotNull(null)
  }
//sampleEnd
  .let(::println)
}
// println: "1"
// res: None