System Overview

The LMNtal compiler (lmnc) first compiles LMNtal source files into intermediate code. It then translates the intermediate code into Java programs, which is in turn compiled into Java bytecode and packaged into a .jar (Java archive) file.

You can also execute the intermediate code interpretively (rather than translating them into Java) by using the lmntal command or lmnc with the --interpret option.

When invoked without a source filename, the LMNtal system enters the read-eval-print loop (REPL) mode in which expressions are executed interpretively.

The system comes with a library API. In addition, you can define your own libraries to be used with your programs. See How to create libraries (below) for details about libraries.

LMNtal programs transtaled into Java bytecode run an order of magnitude faster than the interpreted intermediate code.

How to Use

(Note to Cygwin users: When you run LMNtal (version 0.80 or earlier) on Cygwin, please use lmnc_cyg, lmnr_cyg, and lmntal_cyg instead of lmnc, lmnr, and lmntal. The _cyg suffix is not necessary for version 0.81 and up.)

Using shellscripts (Windows 2000/XP, Cygwin and UNIX/Linux)

On Windows 2000/XP, Cygwin and UNIX/Linux, shellscripts in the bin directory facilitate compilation and execution.

Preparing libraries

(Note: Skip this step unless you have your own library.)

Prepare compiled libraries (how to make lirary .jar files will be explained below) and put them in the lib directory.


$lmnc foo.lmn

Compiler options can be specified either before or after the filename.

$ lmnc -O2 foo.lmn
$ lmnc foo.lmn -d


$ lmnr foo.jar

Runtime options must be specified after the .jar filename.

(ok) $ lmnr foo.jar -g
(no) $ lmnr -t foo.jar

Interactive execution (Read-Eval-Print loop)

$ lmntal

The system enters the interactive when a filename is not specified in the command line. Enter an LMNtal expression (that can spread over multiple lines) and hit the return key twice to execute it. you can also tell the system to start execution with one newline by giving the --immediate option.

The following list shows some interactive-mode commands:

:q                - quit
:h                - see help
:trace | :notrace - set trace mode
:verbose [0-9]    - set verbosity level
:shuffle [0-3]    - set shuffle level

Here is an example of an interactive mode session:

% lmntal [PRESS ENTER]
        LMNtal version 0.70.20060105

Type :h to see help.
Type :q to quit.
Enter an empty line to run the input.

# A=f(f(f(f(f(A))))), c,c, ( c, X=f(Y) :- X=g(Y) ) [PRESS ENTER]
f(g(g(f(f(_4)))),_4), @601
# A=f(f(f(f(f(A))))), c,c, ( c, X=f(Y) :- X=g(Y) ) [PRESS ENTER]
g(f(f(f(g(_24)))),_24), @604

Doing manually (Windows 9x etc.)


  1. When standard or user-defined libraries are used, add their .jar files into the classpath.
  2. Compile the source file:
    $ java runtime.FrontEnd foo.lmn
  3. foo.jar will be created.


  1. Add foo.jar into the classpath.
  2. When standard or user-defined libraries are used, add their .jar files into the classpath.
  3. Invoke the Main class (in foo.jar) as:
    java Main

Command-line options

There are many options for compilation and execution. Popular options include:

-t            - trace mode
-v[0-9]       - set verbosity level ( -v = -v5 )
-s[0-3]       - set shuffle level ( -s = -s3 )
-g            - graphical mode (experimental)

To see the list of all available options, do:

 lmntal --help

A Verbosity Level expresses how verbosely an LMNtal process is displayed.

  0: silence
  1: default
  2: expand link names
  3: shows the contents of rulesets just compiled
  4: expand operators
  5: expand atoms
  6: expand rulesets

A shuffle Level expresses how randomly the execution goes on.

  0: (default) use an atom stack for each membrane
     (atoms are selected in a LIFO manner)
  1: atoms are selected in a system-defined order
     (which is not random or LIFO)
  2: select atoms and membranes randomly from a membrane
  3: select atoms, membranes and rules randomly from a membrane

The graphical Mode (experimental) visualizes program execution. A graphical window will be displayed that visualizes the evolution of hierarchical graph structure. Computation proceeds step by step by pressing the space bar or clicking on the 'Go ahead' button. Atoms can be dragged to arbitrary positions so that the graph may look better. To terminate the execution, close the window manually.

How to create libraries

A library is a program that is prepared (compiled) separately and added to the classpath. A library can be used also with a program running under the --interpret option.

By using shellscripts in the bin directory, you can invoke LMNtal after adding all .jar files located in the lib directory to the classpath.

You can also use the source code of the library by giving the --use-source-library option, in which case the .lmn files in the lib/src directory will be read and compiled on demand.

To create your own program library, compile the program with the --library option:

lmnc --library libhoge.lmn
java runtime.FrontEnd --library libhoge.lmn  (Windows 9x)

Then, move the .jar file to the $LMNTAL_HOME/lib directory.

Classes built by the translator

System rulesets


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