Standard ML of New Jersey
Release Notes

Version 2025.1
February 14, 2025
SML/NJ HOME

https://smlnj.org

FILES

https://smlnj.org/dist/working/2025.1/

Summary

This release is a major milestone in the development of SML/NJ. Thanks to the LLVM backend, we now have native support for the Arm64 (a.k.a. AArch64) architecture running macOS. In addition, this release includes bug fixes and improvements ported from the Legacy repository.

Details

Command-line Tools

The mechanism to create standalone executable programs has been updated to take advantage of the LLVM infrastructure. Specifically, the heap2asm program has been replaced by the heap2obj program that directly converts an exported heap image to a native object file. The heap2exec script has been modified to use heap2obj. Currently we only support static linking of executables. We have also added support for creating executables to the ml-build script. See the manual pages in the documentation for details.

Compiler

  • The code-object API has been changed to make is easier to manage JIT’d code on macOS/arm64. This change should also reduce the amount of data copying when generating binfiles.

  • Switched the backend code generator to use LLVM Version 18.1.8. The llvm10 submodule has been removed.

  • The "Jump-with-Arguments" (JWA) calling convention that we added to LLVM no longer requires that functions have the naked attribute. Instead, we have modified the prologue-epilogue-insertion pass to skip adding code to functions.

  • Ported several fixes and improvements from the legacy repository. These include Legacy Issues #340 and #341), and the addition of some missing fusion rules for conversions via the IntInf.int type.

Runtime System

  • The heap-image format was modified and has a new version number.

  • The representation of big-object regions in the heap was changed to avoid issues with write protection for executable code on macOS/arm64.

  • Collecting basic statistics about memory allocation and GC is now enabled by default in the garbage collector. Access to this information is via the SMLofNJ.Internals.GC structure (see below).

Basis Library

  • Added numGens and nurserySizeInBytes functions to the SMLofNJ.Internals.GC structure, with corresponding runtime-system support.

  • Added the resetCounters and readCounters functions to the SMLofNJ.Internals.GC structure. These functions can be used to get the GC and allocation statistics maintained by the runtime system.

  • Added Unsafe.Array.create0 for creating zero-length polymorphic arrays.

SML/NJ Library

The following changes were made to the Library:

  • Added the combineWith function to the various implementations of the ORD_SET signature.

  • Some minor improvements to hash sets and integer hash tables.

  • Added the decode_strategy mechanism to the UTF8 structure. This mechanism allows specifying how to handle incomplete/invalid multibyte sequences. See Pull Request 334 for more discussion.

  • Added rawArray and rawObject decoders to the JSONDecode structure in the SML/NJ Library.

Installation

  • The installation process has been simplified; the build.sh script now fetches the boot files from smlnj.org if they are not present.

Bugs

Here is a list of the issues that are fixed (or closed) with this release.

Issue Description

285

Date.date incorrectly modifies local time with timezone offset

291

Can’t build 2024.2 because of problem with ASDL C++ library

294

compiler bug aborts build of istari

295

Incorrect constant folding of word equality

We also fixed the following bugs that did not have issues associated with them (or were bug fixes ported from the legacy repository):

Supported systems

We believe that SML/NJ will build and run on the following systems, but have only tested some of them:

Architecture Operating System Status

AMD64

macOS 14 (Sonoma)

macOS 15 (Sequoia)

Tested

Ubuntu 20.04.6 LTS

Ubuntu 22.04.2 LTS

Tested

 

Arm64

macOS 15 (Sequoia)

Tested