MLton

The SML/NJ Library is a collection of libraries that are distributed with SML/NJ. Due to differences between SML/NJ and MLton, these libraries will not work out-of-the box with MLton.

As of 20250523, MLton includes a port of the SML/NJ Library synchronized with SML/NJ version 110.99.8.

Usage

  • You can import a sub-library of the SML/NJ Library into an MLB file with:

    MLB file Description

    $(SML_LIB)/smlnj-lib/Util/smlnj-lib.mlb

    Various utility modules, included collections, simple formating, …​

    $(SML_LIB)/smlnj-lib/Controls/controls-lib.mlb

    A library for managing control flags in an application.

    $(SML_LIB)/smlnj-lib/HashCons/hash-cons-lib.mlb

    Support for implementing hash-consed data structures.

    $(SML_LIB)/smlnj-lib/HTML/html-lib.mlb

    HTML 3.2 parsing and pretty-printing library.

    $(SML_LIB)/smlnj-lib/HTML4/html4-lib.mlb

    HTML 4.01 parsing and pretty-printing library.

    $(SML_LIB)/smlnj-lib/INet/inet-lib.mlb

    Networking utilities; supported on both Unix and Windows systems.

    $(SML_LIB)/smlnj-lib/JSON/json-lib.mlb

    JavaScript Object Notation (JSON) reading and writing library.

    $(SML_LIB)/smlnj-lib/PP/pp-lib.mlb

    Pretty-printing library.

    $(SML_LIB)/smlnj-lib/Reactive/reactive-lib.mlb

    Reactive scripting library.

    $(SML_LIB)/smlnj-lib/RegExp/regexp-lib.mlb

    Regular expression library.

    $(SML_LIB)/smlnj-lib/SExp/sexp-lib.mlb

    S-expression library.

    $(SML_LIB)/smlnj-lib/Unix/unix-lib.mlb

    Utilities for Unix-based operating systems.

    $(SML_LIB)/smlnj-lib/UUID/uuid-lib.mlb

    UUID generating library.

    $(SML_LIB)/smlnj-lib/XML/xml-lib.mlb

    XML library.

  • If you are porting a project from SML/NJ’s CompilationManager to MLton’s ML Basis system using cm2mlb, note that the following maps are included by default:

    # SMLNJ Library
$SMLNJ-LIB                              $(SML_LIB)/smlnj-lib
$smlnj-lib.cm                           $(SML_LIB)/smlnj-lib/Util
$controls-lib.cm                        $(SML_LIB)/smlnj-lib/Controls
$hash-cons-lib.cm                       $(SML_LIB)/smlnj-lib/HashCons
$html-lib.cm                            $(SML_LIB)/smlnj-lib/HTML
$html4-lib.cm                           $(SML_LIB)/smlnj-lib/HTML4
$inet-lib.cm                            $(SML_LIB)/smlnj-lib/INet
$json-lib.cm                            $(SML_LIB)/smlnj-lib/JSON
$pp-lib.cm                              $(SML_LIB)/smlnj-lib/PP
$reactive-lib.cm                        $(SML_LIB)/smlnj-lib/Reactive
$regexp-lib.cm                          $(SML_LIB)/smlnj-lib/RegExp
$sexp-lib.cm                            $(SML_LIB)/smlnj-lib/SExp
$unix-lib.cm                            $(SML_LIB)/smlnj-lib/Unix
$xml-lib.cm                             $(SML_LIB)/smlnj-lib/XML

    This will automatically convert a $/smlnj-lib.cm import in an input .cm file into a $(SML_LIB)/smlnj-lib/Util/smlnj-lib.mlb import in the output .mlb file.

Details

The following changes were made to the SML/NJ Library, in addition to deriving the .mlb files from the .cm files:

  • Compat/either (added): Implements signature EITHER and structure Either: EITHER (see https://github.com/SMLFamily/BasisLibrary/wiki/2015-002-Addition-of-Either-module); used by RegExp Library.

  • Compat/fn (added): Implements signature FN and structure Fn: FN (see https://github.com/SMLFamily/BasisLibrary/wiki/2015-005-Addition-of-Fn-module); used by JSON Library.

  • Compat/mono-buffer (added): Implements signature MONO_BUFFER and structure CharBuffer: MONO_BUFFER (see https://github.com/SMLFamily/BasisLibrary/wiki/2018-001-Addition-of-monomorphic-buffers); used by JSON and PP Libraries.

  • Compat/mono-sequence (added): Implements signature MONO_{ARRAY,VECTOR}{,_SLICE}_EXT and structure Word8Slice: MONO_VECTOR_SLICE_EXT (see https://github.com/SMLFamily/BasisLibrary/wiki/2015-003-Additional-operations-on-sequences and https://github.com/SMLFamily/BasisLibrary/wiki/2018-001-Addition-of-monomorphic-buffers); used by SML/NJ Library.

  • HTML4/pp-init.sml (added): Implements structure PrettyPrint using the SML/NJ PP Library. This implementation is taken from the SML/NJ compiler source, since the SML/NJ HTML4 Library used the structure PrettyPrint provided by the SML/NJ compiler itself.

  • JSON/json-stream-parser.sml and JSON/json-parser.sml (modified): Rewrote use of Unsafe.CharVector.create and Unsafe.CharVector.update; MLton assumes that vectors are immutable.

  • Util/base64.sml (modified): Rewrote use of Unsafe.CharVector.create and Unsafe.CharVector.update; MLton assumes that vectors are immutable.

  • Util/dynamic-array.sml (modified): Rewrote use of Array.fromVector.

  • Util/engine.mlton.sml (added, not exported): Implements structure Engine, providing time-limited, resumable computations using <:MLtonThread:>, <:MLtonSignal:>, and <:MLtonItimer:>.

  • Util/graph-scc-fn.sml (modified): Rewrote use of where structure specification.

  • Util/time-limit.mlb (added): Exports structure TimeLimit, which is not exported by smlnj-lib.mlb. Since MLton is very conservative in the presence of threads and signals, program performance may be adversely affected by unnecessarily including structure TimeLimit.

  • Util/time-limit.mlton.sml (added): Implements structure TimeLimit using structure Engine. The SML/NJ implementation of structure TimeLimit uses SML/NJ’s first-class continuations, signals, and interval timer.

  • Util/utf8.sml (modified): Rewrote use of String.implodeRev (see https://github.com/SMLFamily/BasisLibrary/wiki/2015-003d-STRING).

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