CODEWITHSUNDEEP
scalashapeless
Simon
Simon

Reputation: 6490

Scala shapeless: how to convert a hlist.Mapper to a case class?

I'm brand new to shapeless and I would like to transform a Mapper[mix.type, HNil]#Out to a case class

How can I do this? (Let me know if you need more infos...)

Upvotes: 0

Views: 221

Answers (1)

OlivierBlanvillain
OlivierBlanvillain

Reputation: 7768

That would only work if you define a case class that has the exact same shape that this Mapper#Out. If that's the case, you can create an instance of your case class using shapeless.Generic:

val mout = ... // HList coming from your Mapper
case class A(i: Int, s: String)
shapeless.Generic[A].from(mout): A

That's assuming Generic#Repr and Mapper[mix.type, HNil]#Out are the same type, which you can check using the following:

val mapper = the[Mapper[mix]]
val gen    = the[Generic[A]]
implicitly[mapper#Out =:= gen#Repr] // This only complies if scalac can
                                    // prove equality between these types

Upvotes: 1

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