Running Menter Code

This chapter will cover how to run the command line application. Also learn how to use the Menter Java library.

Installing Menter

Both the command line tool and the Java library are available via:

Since the provided file is a jar file, simply placing it on your PATH won't suffice. It is recommended to configure a script file on your system's PATH that will allow you to execute the jar file conveniently. This will automate the process of calling Java (version >= 8) with the jar file as an argument.

This script file should be called menter.bat or menter.sh, in order to remain consistent with the naming conventions.

Here's an example of a Windows batch file:

@echo off java -jar C:/path/to/menter.jar %*

And a bash script:

#!/bin/bash java -jar /path/to/menter.jar $@

Run Code from the command line

Files

You can run *.mtr from the command line using the menter command.

To run a Menter source file, use the -f or --file flag followed by the path to the file:

menter -f "path/to/file.mtr"

You can also run multiple files at once:

menter -f "path/to/file1.mtr" "path/to/file2.mtr"

Menter will load these files in the order they are specified and execute their contents.
If these files import modules from other files, Menter will only resume executing files after the import is done.

REPL

To get started, it might be easier to use the REPL (Read-Eval-Print Loop). It will launch an interactive shell that will show you the result of each evaluation immediately. To start it, use the repl or --repl flag:

menter repl

In the REPL, you can enter Menter code one line at a time and see the result of each evaluation immediately, similar to the code boxes on this documentation page.

You can combine the repl flag with the file flag to load files into the REPL:

menter repl -f "path/to/file.mtr"

MENTER_HOME

The Menter command line tool will search for Menter source files (*.mtr) in:

  • The current working directory

  • The directory specified by the MENTER_HOME environment variable

  • The directories specified by the -mp and --module-path command line arguments

Menter will scan source files in these directories to detect available modules. These modules are not yet loaded, only if a loaded module imports them.

Documentation Code Boxes

The code boxes on this documentation page can be made interactive by using the -gs or --guide-server flag. This will start a guide server that allows you to execute Menter code in the code boxes.

Possible further options for the guide server are:

  • unsafe, us - Allows importing the io module

  • a number, e.g. 8080 - The port on which the guide server will run

menter -gs unsafe 8080

Once the guide server is running, you may refresh the current page and try out this code box by typing numbers :: 5 or numbers += 5

numbers = range(1, 4)

Troubleshooting Code Boxes

If you are having trouble with the code boxes, you can try the following:

  • Use a locally hosted version of the documentation:
    The guide server will provide you with three URLs. Copy the topmost one and paste it into your browser. It will look something like this:

    Server started on: http://192.168.1.22:8080/docs/introduction?host=192.168.1.22&port=8080

  • Allow via browser settings:
    Your browser may block requests to the guide server. You can allow these requests by clicking on the lock/shield icon in the address bar and then setting the "Improved tracing protection" (or similar prompt) switch to off.

    Why does this happen? This documentation page may be hosted on a https server, but the guide server is hosted on localhost, which uses http. CORS (Cross-Origin Resource Sharing) will block requests from https to http.