@hackage / keiki-codec-json

Changelog

All notable changes to this package are documented in this file. The format follows Keep a Changelog, and this project adheres to the Haskell PVP.

[Unreleased]

[0.1.0.0] — 2026-06-07

Initial Hackage release. Co-released with keiki-0.1.0.0; this package depends on keiki ^>= 0.1.

Added

• Keiki.Codec.JSON — three-method codec class RegFileToJSON (rs :: [Slot]):
  • regFileToJSON :: RegFile rs -> Aeson.Value (strict Value-path encoder).
  • regFileFromJSON :: Aeson.Value -> Either String (RegFile rs) (strict decoder; rejects missing / extra / type-mismatched fields with per-slot error messages).
  • regFileToEncoding :: RegFile rs -> Aeson.Encoding (streaming encoder over Aeson.Series that avoids the O(output-size) intermediate Aeson.Value allocation).
  • A single auto-derived instance for every slot list whose slot types have Aeson.ToJSON + Aeson.FromJSON; users do not write instances by hand.
• Keiki.Codec.JSON.TH — Template Haskell helpers deriveRegFileCodec and deriveRegFileCodecAs that emit three top-level codec functions (<prefix>ToJSON, <prefix>ToEncoding, <prefix>FromJSON) for a record type with deriving (Generic).

Validated against

• GHC 9.12.2 locally on macOS aarch64 and in CI on Ubuntu Linux x86_64 (see .github/workflows/ci.yml).
• 40 hspec assertions, including 4 QuickCheck properties (100 samples each), 9 schema-evolution sensitivity assertions (EP-36 §4 cases #1–9), a pinned golden shape hash, and 10 Keiki.Codec.JSON.TH derivation tests.
• A tasty-bench baseline (bench/baseline.csv) for four representative RegFile size scenarios (multi-party signing, batch reconciliation, ticket aggregate, auction); the Encoding-path is ~1.5× faster than the Value-path on the streaming-motivating case (5,000-entry list) with 33 % less allocation.