Add more DocTests for OptionT
#4311
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| * scala> import cats.data.OptionT | ||
| * scala> import scala.util.Try | ||
| * | ||
| * scala> // prints "5" |
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Is there a good way to test if the side-effects worked properly?
If not, should we even leave those examples in?
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No, and Try is not sufficient for suspending side-effects anyway (nothing in Cats is). We should change these examples.
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Actually, OptionT does not have to deal with side effects:
scala> import cats.data.OptionT, cats.syntax.all._
import cats.data.OptionT
import cats.syntax.all._
scala> val optt = OptionT.some[Either[String, *]](3)
val optt = OptionT(Right(Some(3)))
scala> optt.semiflatTap { case 1 | 2 | 3 => Right("hit!"); case _ => Left("miss!") }
val res0 = OptionT(Right(Some(3)))
scala> optt.semiflatTap { case 0 | 1 | 2 => Right("hit!"); case _ => Left("miss!") }
val res1 = OptionT(Left(miss!))
UPD. I stripped out information on types for better readability.
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That's very clever, I added it to the PR! 👍
armanbilge
changed the title
OptionT
| * | ||
| * Example: | ||
| * {{{ | ||
| * scala> import cats.implicits._ |
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cats.implicits is deprecated.
| * scala> import cats.implicits._ | |
| * scala> import cats.syntax.all._ |
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Thanks, that was news to me. There were actually a bunch of unused cats.implicits._ imports in the Doctests.
I removed them.
| * scala> import cats.implicits._ | ||
| * scala> import cats.data.OptionT | ||
| * | ||
| * scala> type ToString[A] = Function1[A, String] |
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Of course 🤦 - I was so happy I finally found an example for this I didn't even notice.
Updated.
| * scala> import cats.data.OptionT | ||
| * scala> import scala.util.Try | ||
| * | ||
| * scala> // prints "5" |
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No, and Try is not sufficient for suspending side-effects anyway (nothing in Cats is). We should change these examples.
| * scala> import cats.data.OptionT | ||
| * | ||
| * scala> val optionT: OptionT[List, Int] = OptionT[List, Int](List(Some(2), Some(3), Some(4))) | ||
| * scala> optionT.mapFilter(x => Option.when(x % 2 == 0)(x)) |
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CI might not like Option.when on Scala 2.12. I guess we'll find out :)
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Correct, I changed to Option(...).filter(...).
I assume with ~+coreJVM/testOnly **OptionTDoctest (added the +) I should catch those problems, right?
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Possibly. I don't know how ~ and + interact in sbt.
| * scala> val optionT: OptionT[Try, Int] = OptionT[Try, Int](Try(None)) | ||
| * scala> optionT.flatTapNone(Try(println("no value"))).value |
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I think this example is also not really good for the same reason as one for semiflatTap.
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I applied the same idea as in semiflatTap here too. 👍
#2479