• form.lang is a syntax highlighting definition file that introduces the support for FORM in editors that use GtkSourceView (e.g. GNOME text editor gedit, GNOME Builder etc.)

• FORM is a powerful symbolic manipulation system for very large expressions developed by Jos Vermaseren that is widely used in Quantum Field Theory calculations.

The instructions on registering FORM files were adapted from https://help.gnome.org/admin/system-admin-guide/stable/mime-types-custom-user.html.en

• Download the tarball or clone the repository.
• Create the directories for custom language files in your home directory

mkdir -p ~/.local/share/gtksourceview-3.0/language-specs
mkdir -p ~/.local/share/gtksourceview-4/language-specs

• Copy form.lang to ~/.local/share/gtksourceview-3.0/language-specs and ~/.local/share/gtksourceview-4/language-specs

• Create a new mimetype for FORM files in ~/.local/share/mime/packages/text-x-form.xml with the following content

<?xml version="1.0" encoding="UTF-8"?>
<mime-info xmlns="http://www.freedesktop.org/standards/shared-mime-info">
  <mime-type type="text/x-form">
    <comment>new mime type</comment>
    <glob pattern="*.frm"/>
    <glob pattern="*.prc"/>
    <glob pattern="*.h"/>
    <glob pattern="*.hh"/>
  </mime-type>
</mime-info>

• Update your mimetypes database

update-mime-database ~/.local/share/mime

• Create a new .desktop file for FORM in ~/.local/share/applications/form.desktop with the following content

Type=Application
Name=Text Editor
MimeType=text/x-form;
Exec=gedit %f
NoDisplay=true
Icon=gedit

• Update your desktop files database

update-desktop-database ~/.local/share/applications

• Check that FORM files have been registered correctly

touch test.frm
gio info test.frm | grep standard

The output should be

  standard::type: 1
  standard::name: test.frm
  standard::display-name: test.frm
  standard::edit-name: test.frm
  standard::copy-name: test.frm
  standard::icon: text-plain, text-x-generic
  standard::content-type: text/plain
  standard::fast-content-type: text/plain
  standard::size: 0
  standard::allocated-size: 0
  standard::symbolic-icon: text-plain-symbolic, text-x-generic-symbolic, text-plain, text-x-generic

• Open any FORM file with gedit and enjoy the new syntax highlighting

The files formext.lang and vlad-dark.xml show how one can customize the highlighting even further by defining a custom style file. The file formext.lang should be copied to ~/.local/share/gtksourceview-3.0/language-specs just like the regular form.lang (the two can be installed simultaneously), while the file vlad-dark.xml should go into ~/.local/share/gtksourceview-3.0/styles/

Syntax highlighting with form.lang

Syntax highlighting with formext.lang and vlad-dark.xml

To be able to run your FORM scripts directly from gedit, you need to install and activate the External Tools plugin. Then go to Manage External Tools and create a new tool Run FORM with the following script

#!/bin/sh
gnome-terminal -- /bin/bash -c 'cd $GEDIT_CURRENT_DOCUMENT_DIR; ~/bin/form -q $GEDIT_CURRENT_DOCUMENT_NAME; echo Hit Enter to close; read'

You can also assign it a handy shortcut like Super+F2 to make the execution more convenient.

For more information regarding FORM see

• https://www.nikhef.nl/~form/
• https://github.com/vermaseren/form
• https://en.wikipedia.org/wiki/FORM_(symbolic_manipulation_system)

Here are links to some useful material that I extensively used while creating form.lang:

• https://developer.gnome.org/gtksourceview/stable/lang-reference.html
• https://wiki.gnome.org/Projects/GtkSourceView/StyleSchemes
• https://github.com/niklongstone/regular-expression-cheat-sheet

form.lang and formext.lang are covered by the GNU General Public License 3.