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Add FilterIndex instances for java_util
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49 changes: 49 additions & 0 deletions
49
...ptics/arrow-optics/src/main/kotlin/arrow/optics/instances/FilterIndexInstancesJavaUtil.kt
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,49 @@ | ||
| package java_util | ||
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|
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| import arrow.Kind | ||
| import arrow.core.Predicate | ||
| import arrow.core.toT | ||
| import arrow.data.ListK | ||
| import arrow.data.k | ||
| import arrow.data.traverse | ||
| import arrow.optics.Traversal | ||
| import arrow.optics.typeclasses.FilterIndex | ||
| import arrow.typeclasses.Applicative | ||
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| interface MapFilterIndexInstance<K, V> : FilterIndex<Map<K, V>, K, V> { | ||
| override fun filter(p: Predicate<K>) = object : Traversal<Map<K, V>, V> { | ||
| override fun <F> modifyF(FA: Applicative<F>, s: Map<K, V>, f: (V) -> Kind<F, V>): Kind<F, Map<K, V>> = | ||
| ListK.traverse().traverse(s.toList().k(), { (k, v) -> | ||
| FA.map(if (p(k)) f(v) else FA.pure(v)) { | ||
| k to it | ||
| } | ||
| }, FA).let { | ||
| FA.map(it) { | ||
| it.toMap() | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
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| object MapFilterIndexInstanceImplicits { | ||
| @JvmStatic | ||
| fun <K, V> instance(): FilterIndex<Map<K, V>, K, V> = object : MapFilterIndexInstance<K, V> {} | ||
| } | ||
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| interface ListFilterIndexInstance<A> : FilterIndex<List<A>, Int, A> { | ||
| override fun filter(p: (Int) -> Boolean): Traversal<List<A>, A> = object : Traversal<List<A>, A> { | ||
| override fun <F> modifyF(FA: Applicative<F>, s: List<A>, f: (A) -> Kind<F, A>): Kind<F, List<A>> = | ||
| ListK.traverse().traverse(s.mapIndexed { index, a -> a toT index }.k(), { (a, j) -> | ||
| if (p(j)) f(a) else FA.pure(a) | ||
| }, FA).let { | ||
| FA.map(it) { | ||
| it.list | ||
| } | ||
| } | ||
| } | ||
| } | ||
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| object ListFilterIndexInstanceImplicits { | ||
| @JvmStatic | ||
| fun <A> instance(): FilterIndex<List<A>, Int, A> = object : ListFilterIndexInstance<A> {} | ||
| } |
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