Import Upstream version 20180207

[hcoop/debian/mlton.git] / doc / guide / src / SMLofNJStructure.adoc

SMLofNJStructure
================

[source,sml]
----
signature SML_OF_NJ =
   sig
      structure Cont:
         sig
            type 'a cont
            val callcc: ('a cont -> 'a) -> 'a
            val isolate: ('a -> unit) -> 'a cont
            val throw: 'a cont -> 'a -> 'b
         end
      structure SysInfo:
         sig
            exception UNKNOWN
            datatype os_kind = BEOS | MACOS | OS2 | UNIX | WIN32

            val getHostArch: unit -> string
            val getOSKind: unit -> os_kind
            val getOSName: unit -> string
         end

      val exnHistory: exn -> string list
      val exportFn: string * (string * string list -> OS.Process.status) -> unit
      val exportML: string -> bool
      val getAllArgs: unit -> string list
      val getArgs: unit -> string list
      val getCmdName: unit -> string
   end
----

`SMLofNJ` implements a subset of the structure of the same name
provided in <:SMLNJ:Standard ML of New Jersey>.  It is included to
make it easier to port programs between the two systems.  The
semantics of these functions may be different than in SML/NJ.

* `structure Cont`
+
implements continuations.

* `SysInfo.getHostArch ()`
+
returns the string for the architecture.

* `SysInfo.getOSKind`
+
returns the OS kind.

* `SysInfo.getOSName ()`
+
returns the string for the host.

* `exnHistory`
+
the same as `MLton.Exn.history`.

* `getCmdName ()`
+
the same as `CommandLine.name ()`.

* `getArgs ()`
+
the same as `CommandLine.arguments ()`.

* `getAllArgs ()`
+
the same as `getCmdName()::getArgs()`.

* `exportFn f`
+
saves the state of the computation to a file that will apply `f` to
the command-line arguments upon restart.

* `exportML f`
+
saves the state of the computation to file `f` and continue.  Returns
`true` in the restarted computation and `false` in the continuing
computation.