5 Manual page
MLton is run from the command line with a collection of options
followed by a file name and a list of files to compile, assemble, and
link with.
mlton [option ...] file.{c|cm|mlb|o|sml} [file.{c|o|s|S} ...]
The simplest case is to run mlton foo.sml, where foo.sml
contains a valid SML program, in which case MLton compiles the
program to produce an executable foo. Since MLton does not
support separate compilation, the program must be the entire
program you wish to compile. However, the program may refer to
signatures and structures defined in the SML Basis Library.
Larger programs, spanning many files, may be compiled with the ML
Basis system (MLBs). In this case, mlton foo.mlb will compile
the complete SML program described by the basis foo.mlb, which
may specify both SML files and additional bases. See Section 8 for
details.
MLton also supports a limited subset of SML/NJ Compilation Manager
(CM) files. For example, mlton foo.cm will compile the complete
SML program consisting of the concatenation of all the SML files
referred to (either directly or indirectly) by foo.cm. See
Section 11 for details.
5.1 Compile-time options
MLton's options allow you to control the name of the output file,
the verbosity of compile-time messages, and whether or not certain
optimizations are performed. They also allow you to specify which
intermediate files are saved and to stop the compilation process
early, at some intermediate pass, in which case compilation can be
resumed by passing the resulting files to MLton. MLton uses the
input file suffix to determine the type of input program. The
possibilities are .c, .cm, .o, 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
-. In the explanation below and in the usage message, for flags
that take a boolean argument {true|false}, the first value
listed is the default. For example, by default, overflow checking on
is performed on integer arithmetic.
- -align {4|8}
-
Aligns object sizes and doubles in memory by the specified alignment.
On X86, the default is 4 and on Sparc the default is
8.
- -cc-opt option
-
Pass the option to gcc when compiling C code.
- -codegen {native|bytecode|c}
-
Generate native code, byte code, or C code. With -codegen
native, 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 Exn.history. See Section 10.2.5 for details. There is a
performance cost to setting this to true, 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 anns
-
Specify the default annotation values for mlb files. For
example, -default-ann 'warnUnused true' causes unused variable
warnings to be enabled by default. Defaults may be overridden by an
annotation in an mlb file.
- -disable-ann anns
-
Ignore the specified annotations in every ML basis file. You can
supply multiple annotations separated by commas. For example, to see
all match and unused warnings, use -disable-ann 'warnMatch,
warnUnused, forceUsed' -default-ann 'warnUnused true'.
- -export-header file
-
Write to file C prototypes for all of the functions exported
from SML to C. This flag is useful for programs that use _export
expressions (see Section 6.2).
- -ieee-fp {false|true}
-
Cause the native code generator to be pedantic about following the
IEEE floating point standard. By default, it is not, because of the
performance cost. This has no effect with -native false.
- -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|sml}
-
Save intermediate files. If no -keep argument is given, then
only the output file is saved.
g |
generated .S and .c files passed to gcc and the assembler |
o |
object (.o) files |
sml |
SML file |
- -link-opt opt
-
Pass the option to gcc 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
pash an option to the linker, you must use gcc's -Wl,
syntax, e.g., -link-opt '-Wl,--export-dynamic'.
- -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 will gather profiling information. When
such an executable is run, it will produce an mlmon.out file.
See Section 7 for details.
- -profile-branch {false|true}
-
If true, the profiler will separately count the time spent (or bytes
allocated) in each branch of a function definition, case
expression, and if expression.
- -profile-stack {false|true}
-
If true, the profiler will count the time spent (or bytes allocated)
while a function is on the stack.
- -runtime arg
-
Pass argument to the runtime system via @MLton. 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.
- -show-basis file
-
Pretty print to file the basis defined by the input program.
- -show-def-use file
-
Output def-use information to file. Each identifier that is
defined appears on a line, follwed on subequent lines by the position
of each use.
- -stop {f|g|o|sml}
-
Secify pass to stop at.
f |
list of files on stdout (only makes sense when input is foo.cm or foo.mlb) |
g |
generated .S and .c files |
o |
object file |
sml |
SML file (only makes sense when input is foo.cm or foo.mlb) |
tc |
after type checking |
If you compile -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. See Section 14.
- -target-link-opt os opt
-
Like -link-opt, this passes opt to the linker, except it
only passes opt when the target operating system is os.
Valid values for os are:
cygwin,
darwin,
freebsd,
linux,
mingw,
netbsd,
openbsd,
and solaris.
- -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 + intermediate compiler passes |
3 |
2 + some data structure sizes |
5.2 Runtime system options
To control the runtime system, executables produced by MLton take
several optional command line arguments before their usual arguments.
To use these options, the first argument to the executable must be
@MLton
. The optional arguments then follow, must be
terminated by --
, and are followed by any arguments to the
program. The optional arguments are not made available to the
SML program via CommandLine.arguments. For example, a valid
call to hello-world is:
hello-world @MLton gc-summary fixed-heap 10k -- a b c
In the above example, CommandLine.arguments () = ["a", "b",
"c"]. It is also allowed to have a sequence of @MLton
arguments, as in:
hello-world @MLton gc-summary -- @MLton fixed-heap 10k -- a b c
Here are the allowed options.
-
fixed-heap x{k|K|m|M|g|G}
-
Use a fixed size heap of size x, where x is a real number
and the trailing letter indicates its units.
k or K |
1024 |
m or M |
1,048,576 |
g or G |
1,073,741,824 |
A value of 0 means to use almost all the RAM present on the
machine.
- gc-messages
-
Print a message at the start and end of every garbage collection.
- gc-summary
-
Print a summary of garbage collection statistics upon program
termination.
- load-world world
-
Restart the computation with the file specified by world, which must
have been created by a call to MLton.World.save by the same
executable. See Section 10.2.27 for details.
- max-heap x{k|K|m|M|g|G}
-
Run the computation with an automatically resized heap that is never
larger than x, where x is a real number and the trailing
letter indicates the units as with fixed-heap.
- no-load-world
-
Disable load-world. This can be used as an argument to the
compiler via -runtime no-load-world to create executables that
will not load a world. This may be useful to ensure that set-uid
executables do not load some strange world.
- ram-slop x
-
Multiply x by the amount of RAM on the machine to obtain what
the runtime views as the amount of RAM it can use. Typically x
is less than 1, and is used to account for space used by other
programs running on the same machine.
- stop
-
Causes the runtime to stop processing @MLton arguments once the
next -- is reached. This can be used as an argument to the
compiler via -runtime stop to create executables that don't
process any @MLton arguments.
These options can also control MLton, as in
mlton @MLton fixed-heap 0.5g -- foo.sml