16.2 Programs in the separate compilation mode

A program in the separate compilation mode is a set of source files and their interface files. The contents of a source file, denoted here as $\,\langle$ source $\rangle\,$ , are given below.

$\,\langle$ source $\rangle\,$	::=	$($ $\,\langle$ interfaceFileSpec $\rangle\,$ $)?$ $\,\langle$ sourceProgram $\rangle\,$
$\,\langle$ interfaceFileSpec $\rangle\,$	::=	_interface " $\,\langle$ filePath $\rangle\,$ "
$\,\langle$ sourceProgram $\rangle\,$	::=
	$\|$	$\,\langle$ decl $\rangle\,$ $\,\langle$ sourceProgram $\rangle\,$
	$\|$	$\,\langle$ topdecl $\rangle\,$ $\,\langle$ sourceProgram $\rangle\,$

If there is no interface file specification $\,\langle$ interfaceFileSpec $\rangle\,$ in a source file and there is a file of the same name $S$ .smi as that of the source file $S$ .sml (except for its suffix) in the same directory, then that file is implicitly specified as the interface file of the source file. $\,\langle$ filePath $\rangle\,$ is a relative path. Regardless of OS, / (slash) is used for directory separator.

The contents of an interface file, $\,\langle$ interface $\rangle\,$ , consist of $\mbox{$\,\langle$}{\it requireList}\mbox{$\rangle\,$}$ that specifies the set of interface file paths required for the source file, and $\mbox{$\,\langle$}{\it provideList}\mbox{$\rangle\,$}$ that specifies the set of declarations the source file provides to the other compilation units.

$\,\langle$ interface $\rangle\,$	::=	$\,\langle$ requireList $\rangle\,$ $\,\langle$ provideList $\rangle\,$
$\,\langle$ requireList $\rangle\,$	::=
	$\|$	_require $($ local $)?$ $\,\langle$ interfaceName $\rangle\,$ $\,\langle$ requireList $\rangle\,$ $($ init $)?$
	$\|$	_require $($ local $)?$ $\,\langle$ sigFilePath $\rangle\,$ $\,\langle$ requireList $\rangle\,$ $($ init $)?$
$\,\langle$ interfaceName $\rangle\,$	::=	$\,\langle$ smiFilePath $\rangle\,$
	$\|$	$\,\langle$ librarySmiFilePath $\rangle\,$
$\,\langle$ provideList $\rangle\,$	::=
	$\|$	$\,\langle$ provide $\rangle\,$ $\,\langle$ provideList $\rangle\,$
$\,\langle$ provide $\rangle\,$	::=	$\,\langle$ provideInfix $\rangle\,$
	$\|$	$\,\langle$ provideVal $\rangle\,$
	$\|$	$\,\langle$ provideType $\rangle\,$
	$\|$	$\,\langle$ provideDatatype $\rangle\,$
	$\|$	$\,\langle$ provideException $\rangle\,$
	$\|$	$\,\langle$ provideStr $\rangle\,$
	$\|$	$\,\langle$ provideFun $\rangle\,$

$\,\langle$ requireList $\rangle\,$ specifies interface file names (file path or library name) of source files or signature file paths referenced by the source file. local directive in a _require declaration indicates that the specified interface file is only used inside of the source file and does not referenced in $\,\langle$ provideList $\rangle\,$ . init is an annotation indicating that the program corresponding to the specified interface must be executed and precede the program that _requires it. $\,\langle$ provideList $\rangle\,$ specifies the set of declarations the source file provides to the other compilation units.

$\,\langle$ smiFilePath $\rangle\,$ , $\,\langle$ sigFilePath $\rangle\,$ , and $\,\langle$ librarySmiFilePath $\rangle\,$ are file paths relative to the file in which _require is written. Regardless of OS, / (slash) is used for directory separators. If a path does not begins with . (period) and the specified file does not exist, the compiler searches for the file from the load path given in the command line.

SML# provides the following interface libraries.

library smi file name contents

basis.smi Standard ML Basis Library

ml-yacc-lib.smi yacc and lex tools

smlformat-lib.smi SMLFormat formatter generator

smlnj-lib.smi Standard ML of New Jersey library

ffi.smi C FFI support library

thread.smi Multithread library

reify.smi Dynamic typing library

smlunit-lib.smi SMLUnit tool

library smi file name	contents
basis.smi	Standard ML Basis Library
ml-yacc-lib.smi	yacc and lex tools
smlformat-lib.smi	SMLFormat formatter generator
smlnj-lib.smi	Standard ML of New Jersey library
ffi.smi	C FFI support library
thread.smi	Multithread library
reify.smi	Dynamic typing library
smlunit-lib.smi	SMLUnit tool

The following summarizes $\,\langle$ provide $\rangle\,$ specifications corresponding to declarations.

•

Correspondence between core declarations and their interfaces

declaration ( $\,\langle$ decl $\rangle\,$ ) corresponding provide ( $\,\langle$ provide $\rangle\,$ )

$\,\langle$ infixDecl $\rangle\,$ $\,\langle$ provideInfix $\rangle\,$

$\,\langle$ valDecl $\rangle\,$ $\,\langle$ provideVal $\rangle\,$

$\,\langle$ valRecDecl $\rangle\,$ $\,\langle$ provideVal $\rangle\,$

$\,\langle$ funDecl $\rangle\,$ $\,\langle$ provideVal $\rangle\,$

$\,\langle$ datatypeDecl $\rangle\,$ $\,\langle$ provideData $\rangle\,$

$\,\langle$ typeDecl $\rangle\,$ $\,\langle$ provideType $\rangle\,$

$\,\langle$ exceptionDecl $\rangle\,$ $\,\langle$ provideException $\rangle\,$

$\,\langle$ localDecl $\rangle\,$

•

Correspondence between module delcarations and their interfaces

declaration ( $\,\langle$ topdecl $\rangle\,$ ) corresponding provide ( $\,\langle$ provide $\rangle\,$ )

$\,\langle$ strDecl $\rangle\,$ $\,\langle$ provideStr $\rangle\,$

$\,\langle$ sigDecl $\rangle\,$

$\,\langle$ functorDecl $\rangle\,$ $\,\langle$ provideFun $\rangle\,$

$\,\langle$ localTopdecl $\rangle\,$

Signature files are directly referenced in the interface through _require $\,\langle$ sigFilePath $\rangle\,$ .

declaration ( $\,\langle$ decl $\rangle\,$ )	corresponding provide ( $\,\langle$ provide $\rangle\,$ )
$\,\langle$ infixDecl $\rangle\,$	$\,\langle$ provideInfix $\rangle\,$
$\,\langle$ valDecl $\rangle\,$	$\,\langle$ provideVal $\rangle\,$
$\,\langle$ valRecDecl $\rangle\,$	$\,\langle$ provideVal $\rangle\,$
$\,\langle$ funDecl $\rangle\,$	$\,\langle$ provideVal $\rangle\,$
$\,\langle$ datatypeDecl $\rangle\,$	$\,\langle$ provideData $\rangle\,$
$\,\langle$ typeDecl $\rangle\,$	$\,\langle$ provideType $\rangle\,$
$\,\langle$ exceptionDecl $\rangle\,$	$\,\langle$ provideException $\rangle\,$
$\,\langle$ localDecl $\rangle\,$

declaration ( $\,\langle$ topdecl $\rangle\,$ )	corresponding provide ( $\,\langle$ provide $\rangle\,$ )
$\,\langle$ strDecl $\rangle\,$	$\,\langle$ provideStr $\rangle\,$
$\,\langle$ sigDecl $\rangle\,$
$\,\langle$ functorDecl $\rangle\,$	$\,\langle$ provideFun $\rangle\,$
$\,\langle$ localTopdecl $\rangle\,$

We show simple examples below.

•

Example 1 (Using the Standard ML Basis Library)

file code

hello.sml val _ = print "Welcome to SML＃\n"

hello.smi _require "basis.smi"

Compilation and execution

$ smlsharp hello.sml
$ ./a.out
Welcome to SML＃ $

file	code
hello.sml	val _ = print "Welcome to SML＃\n"
hello.smi	_require "basis.smi"

•

Example 3 (separate compilation)

file	code
hello.sml	val _ = puts "Welcome to SML#"
hello.smi	_require "puts.smi"
puts.sml	val puts = _import "puts" : string -> int
puts.smi	val puts : string -> int

Compilation and execution

$ smlsharp -c hello.sml
$ smlsharp -c puts.sml
$ smlsharp -o hello hello.smi
$ ./hello
Welcome to SML# $