typelevel / typelevel/frameless

Add TypedEncoder for shapeless Record.

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#777 3 comments 0 reactions 0 assignees View on GitHub

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Dominant language
Scala
Stars
895
Forks
135
Avg merge
1d 16h
Merged PRs (30d)
3

Description

Since RecordEncoder is already converting any product type into shapeless Record:

class RecordEncoder[F, G <: HList, H <: HList](
    implicit
    i0: LabelledGeneric.Aux[F, G],
    i1: DropUnitValues.Aux[G, H],
    i2: IsHCons[H],
    fields: Lazy[RecordEncoderFields[H]],
    newInstanceExprs: Lazy[NewInstanceExprs[G]],
    classTag: ClassTag[F])
    extends TypedEncoder[F] {
...

The only thing required is to break it into 2 stages, such that the intermediate HList/Record representation could serve as a more flexible type-level schema, it could even approximate the capability of the abandoned TypedDataFrame

I also realised that i0~i2 are not used in the function body. i2 is important to not accept HNil, but are i0 & i1 necessary?

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the RecordEncoder definition shown in the issue and trace its TypedEncoder implementation and implicit parameters. Determine how a two-stage conversion can expose the intermediate HList/Record schema, verify whether i0 and i1 are required, and define completion as a reviewed API and design that supports non-empty records.

Written by the indexing model from the issue text.

Assessment

Tech stack
scala
Domain
data
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
30/100

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