.M File Extension

You can open an M file with The MathWorks MATLAB (multiplatform). To open an M file, select Open from the "HOME" or "EDITOR" tabs, choose the M file, then select Open.

Opening an M file with a text or source code editor

Since M files store plain text, you can open them with a text editor, such as Microsoft Notepad (Windows) or Apple TextEdit (Mac), or a source code editor. However, most users open and edit M files with MATLAB since the app provides helpful editing tools not available with third-party apps.

Mercury was written in order to provide a robust language for large real world applications. It includes several error-checking features not provided by other logic programming languages. For example, the language incorporates static analysis that can catch type checking errors before runtime. This enables greater assurance over the correctness of the program and also allows the compiler to generate more efficient code. However, the developer must specify each of the "type," "mode," and "determinism" constructs while programming, which is not necessarily required by other languages.

NOTE: The developmental version of the Mercury compiler is currently distributed in a source code format and does not include compiler binaries. However, a Windows port of Mercury, called winmercury, includes binaries. It also includes Vim syntax highlighting files for source code editing.

NOTE: In order to play M files with FMPMD2000, you need to download the WinFMP.dll and PMDWin.dll files, which are available from the same location.

If you want to view or edit an M file's contents, you can open it with any text editor. However, you're best off viewing and editing M files with Wolfram Workbench, an Eclipse-based IDE meant to be used alongside Mathematica.

To use an M file with Wolfram Mathematica:

1. Select File → Open.
2. Navigate to and open your M file.

Mathematica will then import the inputs your M file contains into your current NB file. In some cases, you will have to evaluate these inputs manually. In others, Mathematica will automatically ask you whether you want to evaluate the inputs.

You can find more information about how to use M files with Mathematica here.

How to export an M file from an NB file

In some cases, you may want to save Wolfram Language packages that you've created within an NB file as their own, separate M file. To do this manually:

1. Mark the Input cells that contain your Wolfram Language package's inputs as Initialization cells.
2. Select File → Save As from Mathematica's menu bar.
3. Save your NB file as an M file.

Instead of overwriting your NB file, Mathematica will create a new M file that includes the contents of all the cells you marked as Initialization cells. (This file will also include your NB file's other contents, but those contents will be commented out.)

If you want to automatically save all Wolfram Language packages you create within NB files as separate M files, you can do so by adjusting Mathematica's settings as follows:

1. Select Preferences → Option Inspector → Notebook Options → File Options → AutoGenerated Package.
2. Set AutoGeneratedPackage to Automatic.

From now on, when you save an NB file that contains Initialization cells, Mathematica will also save an M file that includes the contents of the NB file's Initialization cells (and the NB file's other contents, commented out).