SML NJ Related Projects

SMLNJ Related Projects

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Development/maintenance projects for the SML/NJ compiler, tools, and libraries

The following might be potential tasks for new volunteers joining the SML/NJ Fellowship, or opportunities to "steal" and adapt existing work.

1. Reimplementation of the (classic) SML/NJ match compiler

• presentation at ML Family Workshop, 2022

• need to document in a tech report

• [DBM: Done, 2021]

2. Design,implementation, and documentation of a new, improved prettyprinting library

• synthesis of ideas from Oppen, PPML, Hughes-Wadler-Leijen

• [DBM: (Done), 2022-3]

3. Revamping and modernizing the SML/NJ type checker

• improved type error messages

• new treatment of type variables and type constructor variables

• [equality polymorphism elimination? (while retaining "equality types")]

• [DBM: 2023- ...]

4. Redesigning and reimplementing the SML/NJ module system

• in conjunction with the reworking of the type system

• Successor ML redesign

• new formal semantics and its documentation

• functor application "inlining" for optimization

• [DBM: 2023- ...]

5. Reimplementation and simplification of the FLINT type system

• revision of hash-consing scheme

• simplified approach to type closures (replacing semi-Nadathur closures)

• elimination/replacement of deBruijn type variables (using only conventional "named" type variables)

6. Revision or replacement of the FLINT middle end

• Reppy-Shivers plans?

• [JHR: ...]

7. Support for the Windows port of SML/NJ

• platform-specific libraries and OS interfaces

• maintain Windows installer

• investigate building on Linux for Windows

• updating, documentation, etc.

8. Simplification and documentation of the SML/NJ build process

9. Revised compiler architecture

• continuing evolution toward fully library-based compiler

• more balanced support for interactive system and batch compilation

• better support for stand-alone SML applications

10. New memory management in runtime system

• [JRH: ongoing]

11. Preservation, maintenance, improvement of MLRISC code generation library

• hedging the bet on llvm code generation

12. RISCV code generator

• based on llvm or MLRISC?

13. New or improved tools and libraries

• HTML5 support

• porting selected Python libraries?

14. Adding support for Unicode characters and strings

15. Package manager and distribution system for libraries

• Examples: Hackage for Haskell, OCaml package management?

16. Compiler distribution and installation

• maintain OS-specific compiler installers (Mac, Linux, Windows)

• building packages for Linux package managers

• Macports and Homebrew on macOS

• improved support and documenation for building from source

17. Microsoft LSP (Language Server Protocol) support for SML/NJ

• interacts with front-end representations (types, absyn) and therefore is related to projects 3 and 4.

• See Ariel Davis's Millet GitHub project.

18. Hand-made recursive descent parser with good syntax error messages

• Does such a thing already exist? (e.g. in MLton or in Sam Westrick's [smlfmt] (https://github.com/shwestrick/smlfmt])?

19. Revamping the compiler test suits and testing methodology.

20. Recreate the index for "The Definition of Standard ML (Revised)". See https://github.com/SMLFamily/SML-The-Living-Language/issues/1.

21. An SML/NJ Handbook

• Chapters providing detailed documentation of the implementations of the main components of the compiler, the runtime system, and associated tools and libraries.

DBM, 2023.1.14