MLton’s compile-time options control the name of the output file, the
verbosity of compile-time messages, and whether or not certain
optimizations are performed. They also can specify which intermediate
files are saved and can stop the compilation process early, at some
intermediate pass, in which case compilation can be resumed by passing
the generated files to MLton. MLton uses the input file suffix to
determine the type of input program. The possibilities are .c
,
.mlb
, .o
, .s
, and .sml
.
With no arguments, MLton prints the version number and exits. For a
usage message, run MLton with an invalid switch, e.g. mlton -z
. In
the explanation below and in the usage message, for flags that take a
number of choices (e.g. {true|false}
), the first value listed is the
default.
Options
-
-align n
Aligns object in memory by the specified alignment (
4
or8
). The default varies depending on architecture. -
-as-opt option
Pass option to
cc
when compiling assembler code. If you wish to pass an option to the assembler, you must usecc
’s-Wa,
syntax. -
-cc cc
Specify the executable for the C compiler. The C compiler is also invoked to compile assembly (
.s
files) to object code (.o
files) and to link object code into an executable. -
-cc-opt option
Pass option to
cc
when compiling C code. -
-codegen {native|amd64|c|llvm|x86}
Generate native object code via amd64 assembly, C code, LLVM code, or x86 code or C code. With
-codegen native
(-codegen amd64
or-codegen x86
), MLton typically compiles more quickly and generates better code. -
-const name value
Set the value of a compile-time constant. Here is a list of available constants, their default values, and what they control.
-
Exn.keepHistory {false|true}
Enable
MLton.Exn.history
. See MLtonExn for details. There is a performance cost to setting this totrue
, both in memory usage of exceptions and in run time, because of additional work that must be performed at each exception construction, raise, and handle.
-
-
-default-ann ann
Specify default ML Basis annotations. For example,
-default-ann 'warnUnused true'
causes unused variable warnings to be enabled by default. A default is overridden by the corresponding annotation in an ML Basis file. -
-default-type type
Specify the default binding for a primitive type. For example,
-default-type word64
causes the top-level typeword
and the top-level structureWord
in the Basis Library to be equal toWord64.word
andWord64:WORD
, respectively. Similarly,-default-type intinf
causes the top-level typeint
and the top-level structureInt
in the Basis Library to be equal toIntInf.int
andIntInf:INTEGER
, respectively. -
-disable-ann ann
Ignore the specified ML Basis annotation in every ML Basis file. For example, to see all match and unused warnings, compile with
-default-ann 'warnUnused true' -disable-ann forceUsed -disable-ann nonexhaustiveMatch -disable-ann redundantMatch -disable-ann warnUnused
-
-export-header file
Write C prototypes to file for all of the functions in the program exported from SML to C.
-
-ieee-fp {false|true}
Cause the x86 native code generator to be pedantic about following the IEEE floating point standard. By default, it is not, because of the performance cost. This only has an effect with
-codegen x86
. -
-inline n
Set the inlining threshold used in the optimizer. The threshold is an approximate measure of code size of a procedure. The default is
320
. -
-keep {g|o}
Save intermediate files. If no
-keep
argument is given, then only the output file is saved.g
generated
.c
and.s
files passed tocc
and generated.ll
files passed tollvm-as
o
object (
.o
) files -
-link-opt option
Pass option to
cc
when linking. You can use this to specify library search paths, e.g.-link-opt -Lpath
, and libraries to link with, e.g.,-link-opt -lfoo
, or even both at the same time, e.g.-link-opt '-Lpath -lfoo'
. If you wish to pass an option to the linker, you must usecc
’s-Wl,
syntax, e.g.,-link-opt '-Wl,--export-dynamic'
. -
-llvm-as llvm-as
Specify the executable for the LLVM
.ll
to.bc
assembler; can be used to select a specific version of the tool (e.g.,-llvm-as llvm-as-14
). -
-llvm-as-opt option
Pass option to
llvm-as
when assembling (.ll
to.bc
) LLVM code. -
-llvm-llc llc
Specify the executable for the LLVM
.bc
to.o
system compiler; can be used to select a specific version of the tool (e.g.,-llvm-as llc-14
). -
-llvm-llc-opt option
Pass option to
llc
when compiling (.bc
to.o
) LLVM code. -
-llvm-opt opt
Specify the executable for the LLVM
.bc
to.bc
optimizer; can be used to select a specific version of the tool (e.g.,-llvm-opt opt-14
). -
-llvm-opt-opt option
Pass option to
opt
when optimizing (.bc
to.bc
) LLVM code. -
-mlb-path-map file
Use file as an ML Basis path map to define additional MLB path variables. Multiple uses of
-mlb-path-map
and-mlb-path-var
are allowed, with variable definitions in later path maps taking precedence over earlier ones. -
-mlb-path-var name value
Define an additional MLB path variable. Multiple uses of
-mlb-path-map
and-mlb-path-var
are allowed, with variable definitions in later path maps taking precedence over earlier ones. -
-output file
Specify the name of the final output file. The default name is the input file name with its suffix removed and an appropriate, possibly empty, suffix added.
-
-profile {no|alloc|count|time}
Produce an executable that gathers profiling data. When such an executable is run, it produces an
mlmon.out
file. -
-profile-branch {false|true}
If true, the profiler will separately gather profiling data for each branch of a function definition,
case
expression, andif
expression. -
-profile-stack {false|true}
If
true
, the executable will gather profiling data for all functions on the stack, not just the currently executing function. See ProfilingTheStack. -
-profile-val {false|true}
If
true
, the profiler will separately gather profiling data for each (expansive)val
declaration. -
-runtime arg
Pass argument to the runtime system via
@MLton
. See RunTimeOptions. The argument will be processed before other@MLton
command line switches. Multiple uses of-runtime
are allowed, and will pass all the arguments in order. If the same runtime switch occurs more than once, then the last setting will take effect. There is no need to supply the leading@MLton
or the trailing--
; these will be supplied automatically.An argument to
-runtime
may contain spaces, which will cause the argument to be treated as a sequence of words by the runtime. For example the command line:mlton -runtime 'ram-slop 0.4' foo.sml
will cause
foo
to run as if it had been called like:foo @MLton ram-slop 0.4 --
An executable created with
-runtime stop
doesn’t process any@MLton
arguments. This is useful to create an executable, e.g.,echo
, that must treat@MLton
like any other command-line argument.% mlton -runtime stop echo.sml % echo @MLton -- @MLton --
-
-show-basis file
Pretty print to file the basis defined by the input program. See ShowBasis.
-
-show-def-use file
Output def-use information to file. Each identifier that is defined appears on a line, followed on subsequent lines by the position of each use.
-
-stop {f|g|o|tc}
Specify when to stop.
f
list of files on stdout (only makes sense when input is
foo.mlb
)g
generated
.c
and.s
fileso
object (
.o
) filestc
after type checking
If you compile with
-stop g
or-stop o
, you can resume compilation by running MLton on the generated.c
and.s
or.o
files. -
-target {self|…}
Generate an executable that runs on the specified platform. The default is
self
, which means to compile for the machine that MLton is running on. To use any other target, you must first install a cross compiler. -
-target-as-opt target option
Like
-as-opt
, this passes option tocc
when compliling assembler code, except it only passes option when the target architecture, operating system, or arch-os pair is target. -
-target-cc-opt target option
Like
-cc-opt
, this passes option tocc
when compiling C code, except it only passes option when the target architecture, operating system, or arch-os pair is target. -
-target-link-opt target option
Like
-link-opt
, this passes option tocc
when linking, except it only passes option when the target architecture, operating system, or arch-os pair is target. -
-verbose {0|1|2|3}
How verbose to be about what passes are running. The default is
0
.0
silent
1
calls to compiler, assembler, and linker
2
1, plus intermediate compiler passes
3
2, plus some data structure sizes