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#arrow-contributors
- p
pakoito
07/22/2018, 4:30 PM@pakoito uploaded a file:We parallel▾
- p
pakoito
07/22/2018, 4:30 PMcc @raulraja - p
pakoito
07/22/2018, 4:31 PM@Eugenio correct. Nested is an erasure trick to emulate type lambdas / projections from Scala - e
Eugenio
07/22/2018, 4:34 PMfor now I've done this:Copy codesealed class Nested<F: KindType, G: KindType> : Witness<Nested<F, G>>() { companion object: Nested<Kind_, Kind_>() { @Suppress("UNCHECKED_CAST") operator fun <F: KindType, G: KindType> invoke() = this as Nested<F, G> } - e
Eugenio
07/22/2018, 4:34 PMit's a recursive witness! 😄 - e
Eugenio
07/22/2018, 4:35 PMthis way it's allowed to doCopy codeKind<Nested<F, G>, A> - e
Eugenio
07/22/2018, 4:36 PMso, essentially, it's both a witness and a type - p
pakoito
07/22/2018, 4:51 PM👍 - p
pakoito
07/22/2018, 4:51 PMneat - e
Eugenio
07/22/2018, 8:48 PMphew, so, here's what it looks like @pakoito: https://github.com/Takhion/arrow/commit/df3512cd54a455ce424d2ef65056f5073acd2fd6 - e
Eugenio
07/22/2018, 8:48 PMI have to admit that having to specify the generic type parameter makes it a lot more clear what everything is doing - p
pakoito
07/22/2018, 8:49 PMRIP Github - p
pakoito
07/22/2018, 8:49 PMlooked good so far 😄 - p
pakoito
07/22/2018, 8:50 PMwhy does the witness have to be an object, why can’t it be a class with a private constructor? - p
pakoito
07/22/2018, 8:50 PM*marker - p
pakoito
07/22/2018, 8:51 PMobject ${hk.markerName} : arrow.Witness<${hk.kindName}<${hk.tparams.joinToString { "*" }}>>() - e
Eugenio
07/22/2018, 8:52 PMbecause it's easier than having a companion object - e
Eugenio
07/22/2018, 8:52 PMthis way, if you need to pass it around as an instance, you can - p
pakoito
07/22/2018, 8:54 PMI’m not sure I follow, these markers are only used as the generic parameter. Do we want to use them as place where to put the APIs? - p
pakoito
07/22/2018, 8:54 PMinstead of the companion objects - p
pakoito
07/22/2018, 8:55 PMother than that, looks good. Is there any file in particular other than the ones atop the diff that is worth checking? - p
pakoito
07/22/2018, 8:55 PMComposed/Nested I guess - e
Eugenio
07/22/2018, 9:13 PMyeah those mostly - e
Eugenio
07/22/2018, 9:13 PMwhen I open the PR (not today) I'll link all non-standard modifications - e
Eugenio
07/22/2018, 9:14 PMwhat I meant about having access to the instance is that sometimes it's useful to have an instance to pass around - e
Eugenio
07/22/2018, 9:14 PMespecially for type inference - e
Eugenio
07/22/2018, 9:15 PMbut I'm def. not married to any of this, I mostly wanted to see how it would look like - e
Eugenio
07/22/2018, 9:16 PM - p
pakoito
07/22/2018, 9:25 PMit’s not jumping -.- which file are your linking? - e
Eugenio
07/22/2018, 10:01 PM