softwaremill / softwaremill/quicklens
using quicklens with tagged datatypes
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Description
Hi,
I'm using quicklens 1.4.11 and com.softwaremill.common tagging v 2.2.0. I'm unable to modify a value containing tagged datatypes. For example :
import com.softwaremill.tagging._
import com.softwaremill.quicklens._
case class A(data: String)
sealed trait B
type C = A @@ B
case class D(value: C)
val a: C = A("test").taggedWith[B]
val d = D(a)
d.modify(_.value.data).setTo("modified")
This does not compile :
[error] type mismatch;
[error] found : A
[error] required: C
[error] (which expands to) A with AnyRef{type Tag <: B}
[error] L145: d.modify(_.value.data).setTo("modified")
I understand why this doesn't compile but I was wondering if there is any way around this.
I also tried using shapeless tagging (it uses a trait instead of a type for tagging) but the issue remains.
Apologies if this has been asked before, I searched open & closed issues but could not find anything relevant.
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Research direction
The issue names no repository files or tests. Start by reproducing the tagged-datatype example with Scala, quicklens 1.4.11, and tagging 2.2.0, then locate the modification entry point and existing tagged-value handling. Done means the example compiles with a supported behavior or the limitation is documented, with a regression test if applicable.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- scala
- Domain
- developer-experience
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 28/100