MCMS Custom codec for complex custom types

[JohnChangUK]

Add Daml Codec Generator

Auto-generate *CodecGen.daml files from *Types.daml source files, eliminating hand-written codec boilerplate.

How it works

LRPoolTypes.daml → go run ./contracts/cmd/damlcodecs → LRPoolTypesCodecGen.daml

The generator:

1. Parses *Types.daml files to extract record/variant definitions
2. Maps each field type to its encode/decode function
3. Outputs a complete codec file

Type resolution:

• Primitives (Int, Bool, Numeric 0, etc.) → built-in codec functions
• Records/variants in same file → generates codecs for them automatically
• External types (RawInstanceAddress, InstrumentId, CustomContext) → configured via customCodecs map

Usage

1. cd <your_repo>
2. go run ./contracts/cmd/damlcodecs
3. daml build --all

Files added

go-daml:

• codegen/damlparser/ - Parses Daml source files
• codegen/damltemplate/ - Generates codec output

<your_repo>:

• contracts/cmd/damlcodecs/main.go - CLI tool with project-specific config

Why parse source files?

Daml compiles packages atomically. The codec imports the types, so you can't compile types without the codec existing. Parsing source files (not compiled DARs) breaks this circular dependency.

[github-actions]

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