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Limbo

Language type:

S - block-structured

Description:

Limbo is a block-structured, procedural language intended for application and embedded system development. It is the main programming language of the Lucent Inferno operating system.
The distinguishing characteristics of Limbo are its simplicity, its support for modularity, and its support for multi-threaded and distributed processing.
Limbo is strongly typed, all variable and function types are explicitly declared, and type checking is performed at compile-time and module load-time. Primitive data types in the language are ints (3 sizes), reals, and strings (using Unicode). Limbo also supports lists, arrays, tuples, channels, and definition of abstract data types. A Limbo program is comprised of separate modules, the interface and implementation of a module are separate and one interface can have several implementations. (Inheritance is not supported, though, so Limbo cannot be considered and object-oriented programming language.)
The current Limbo compiler produces byte-codes that are either interpreted directly or transformed into native code on-the-fly by the Limbo run-time engine. The Limbo run-time system provides all channel and process management, as well as memory management and garbage collection. I/O and system interface facilities are provided by a set of standard 'library' modules.
Limbo's run-time environment has been ported to various Unix editions, Windows, Plan9, and other operating systems, as well as directly onto various CPU architectures. The Inferno system is available free from Lucent, but requires registration.

Origin:

Doward, Winterbottom, and Pike, Lucent Technologies, 1996.

See Also:

Pascal    C    Modula-2    Java    Alef    CSP    Tcl   

Remarks:

Limbo includes inter-process communication channels as primitive language type. These channels can be used to send any data object between Limbo processes on the same machine or across a network. The Inferno system includes full cryptographic security for the communication link.
Limbo is intended to be the language for all applications under Inferno. Therefore, it must have a GUI system; the current GUI system for Limbo is a version of Tk.
Limbo is occasionally referred to as "Network C," even though it really resembles several other languages as closely as it resembles C.

Links:

Inferno Limbo Tutorial

A comparison of Limbo and Java

Main Inferno web site

Date:

Last updated 8/5/08

Sample code:

# A simple program to sum up some numbers
# presented on the command line, from 
# Bob Pike's forthcoming book on Limbo.
        implement Sum;
        
        include "sys.m";
                sys: Sys;  
        include "draw.m";
        
        Sum: module
        {
                init: fn(context: ref Draw->Context, argl: list of string);
        };
        
        init(context: ref Draw->Context, argl: list of string)
        {
                sys = load Sys Sys->PATH;
                argl = tl argl; # ignore command name
                if(len argl == 0){
                        sys->print("usage: sum numbers....\n");
                        return;
                }
                sum := 0.0;
                while(argl != nil){
                        arg := hd argl;
                        sys->print("%s", arg);
                        sum += real arg;
                        argl = tl argl;
                        if(argl != nil)
                                sys->print(" + ");
                }
                sys->print(" = %g\n", sum);
        }

Descriptions in this dictionary are ©1997-99 Neal Ziring. Some examples copyright of their respective authors. Some technologies and languages are trademarked. Permission to copy descriptions is granted as long as authorship credit is preserved.

Comments on this dictionary, corrections and suggestions, are all welcome. Please use email, the address is ziring@home.com