Just-in-time-decoded types #413
Conversation
This reverts commit ca92702.
| Defn.Type( | ||
| List(Mod.Opaque()), | ||
| Type.Name(name), | ||
| Nil, | ||
| extending.fold[Type](t"_root_.io.circe.Json")(name => Type.Name(name)), | ||
| Type.Bounds(None, extending.map(name => Type.Name(name))) | ||
| ) |
There was a problem hiding this comment.
Can't use quasi-quotes here unfortunately.
There was a problem hiding this comment.
Understood. Also, bummer. Maybe add a comment with this?
There was a problem hiding this comment.
I hadn't followed-up on the issue, looks like it may be fixed soon (or possibly already in the latest release). Will check.
| @@ -497,11 +544,17 @@ trait Generator { | |||
| def valName(prefix: String): Pat.Var = Pat.Var(Term.Name(s"$prefix$name")) | |||
|
|
|||
| val eqDef = Option.when(catsEq)( | |||
| q"implicit val ${valName("eq")}: cats.Eq[$n] = cats.Eq.fromUniversalEquals" | |||
| if (jitDecoder) | |||
| q"implicit val ${valName("eq")}: cats.Eq[$n] = _root_.io.circe.Json.eqJson.asInstanceOf[cats.Eq[$n]]" | |||
There was a problem hiding this comment.
Maybe summon[Eq[Json]] in case it changes name?
There was a problem hiding this comment.
That's pretty much what I did at first 😅 the problem is, the compiler can't distinguish the opaque type from Json, so summon[Eq[Json] ends up attempting to circularly summon the very implicit we are defining 😂
in case it changes name?
This would be binary-breaking anyway, so unlikely.
There was a problem hiding this comment.
I see. I guess we could summon it once per file and assign it a name ourselves. But may be overkill.
|
I'm going to close this issue for the time being. |
This implements an alternate code generation scheme, targeting Scala 3.
Instead of generating case classes,
opaque types are used that are backed by CirceJson. Thenextensionmethods expose the fields of the type. Behind-the-scenes, these are implemented by "just-in-time" (JIT) decoding of that field to its type.This has some limitations, including:
Json. Anyway, opaque sum type cannot be sealed, it's not really a sum type at all anymore. This can be mitigated by adding afold-like operation to the parent type.It should be possible to mix JIT-decoded types with members that are user-defined classes, and vice versa. This is because everything works in terms of
Decoders, the only question is when thedecodehappens. The decoder for a JIT-decoded type is the identity functionJson => Json, and further decoding is deferred till field access.