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Favor Either and IO instead of Try #1478

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merged 7 commits into from Jun 9, 2019
Merged

Favor Either and IO instead of Try #1478

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2c37e70
Add catch constructor to Either
Jun 8, 2019
f9dddf8
Add other catch constructor to Either
Jun 8, 2019
25bef35
Add deprecation notices in favor of Either
Jun 8, 2019
0f62b53
Fix ReplaceWith
Jun 8, 2019
a25bd44
Merge branch 'master' into paco-catcheither
pakoito Jun 9, 2019
b6e79b7
Make Either constructors suspend
Jun 9, 2019
09c71d2
Improve Try deprecation notice
Jun 9, 2019
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10 changes: 10 additions & 0 deletions modules/core/arrow-core-data/src/main/kotlin/arrow/core/Either.kt
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Expand Up @@ -189,6 +189,16 @@ sealed class Either<out A, out B> : EitherOf<A, B> {
}

fun <L, R> cond(test: Boolean, ifTrue: () -> R, ifFalse: () -> L): Either<L, R> = if (test) right(ifTrue()) else left(ifFalse())

fun <R> catch(f: () -> R): Either<Throwable, R> =
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This should be suspend fun <R> catch...

catch(::identity, f)

fun <L, R> catch(fe: (Throwable) -> L, f: () -> R): Either<L, R> =
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suspend

try {
f().right()
} catch (t: Throwable) {
fe(t.nonFatalOrThrow()).left()
}
}
}

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16 changes: 16 additions & 0 deletions modules/core/arrow-core-data/src/main/kotlin/arrow/core/Try.kt
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Expand Up @@ -16,8 +16,16 @@ sealed class Try<out A> : TryOf<A> {

companion object {

@Deprecated(
"Try promotes eager execution and works like Either, so it's better if you work with Either or a suspended type like IO",
ReplaceWith("Either.just(a)")
)
fun <A> just(a: A): Try<A> = Success(a)
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This constructor is fine if we use suspend for Try's effects


@Deprecated(
"Try promotes eager execution and works like Either, so it's better if you work with Either or a suspended type like IO",
ReplaceWith("Either.tailRecM(a, f)")
)
tailrec fun <A, B> tailRecM(a: A, f: (A) -> TryOf<Either<A, B>>): Try<B> {
val ev: Try<Either<A, B>> = f(a).fix()
return when (ev) {
Expand All @@ -32,6 +40,10 @@ sealed class Try<out A> : TryOf<A> {
}
}

@Deprecated(
"Try promotes eager execution and works like Either, so it's better if you work with Either or a suspended type like IO",
ReplaceWith("Either.catch(f)")
)
inline operator fun <A> invoke(f: () -> A): Try<A> =
try {
Success(f())
Expand All @@ -43,6 +55,10 @@ sealed class Try<out A> : TryOf<A> {
}
}

@Deprecated(
"Try promotes eager execution and works like Either, so it's better if you work with Either or a suspended type like IO",
ReplaceWith("Either.raiseError(e)")
)
fun raiseError(e: Throwable): Try<Nothing> = Failure(e)
}

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