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Implementation of Result.flatMap(), missing from Kotlin stdlib
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| inline fun <R, T> Result<T>.flatMap(transform: (T) -> Result<R>): Result<R> = | |
| fold({ transform(it) }, { Result.failure(it) }) | |
| fun main() { | |
| getUserInput() | |
| .flatMap { input -> parseInput(input) } | |
| .flatMap { numbers -> calculateMax(numbers) } | |
| .onSuccess { maxNumber -> println("max: $maxNumber") } | |
| .onFailure { throwable -> throwable.printStackTrace() } | |
| } | |
| // fails on empty input | |
| fun getUserInput(): Result<String> = runCatching { readln().ifEmpty { error("empty") } } | |
| // fails on non-numbers | |
| fun parseInput(input: String): Result<List<Int>> = | |
| runCatching { input.split(" ").mapNotNull { if (it.isBlank()) null else it.toInt() } } | |
| // fails on " " input | |
| fun calculateMax(numbers: List<Int>) = runCatching { numbers.maxOf { it } } |
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