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pakoito/lwo.kt

Last active January 17, 2018 16:44
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lwo.kt
inline fun <A, B> A?.fold(crossinline fn: () -> B, crossinline f: (A) -> B): B =
if (this == null) fn() else f(this)
inline fun <A, B> A?.map(crossinline f: (A) -> B): B? = fold({ null }, f)
inline fun <A> A?.orElse(crossinline fn: () -> A): A = fold(fn, { it })
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pakoito commented Nov 16, 2017 •
edited 

val a: Int? = null
val x = a.map { it + 1 }.orElse { 0 }
// 0
val a: Int? = 0
val x = a.map { it + 1 }.orElse { 0 }
// 1

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