This is the homepage of the Macaulay 2 package WeylGroups, written by Baptiste Calmès and Viktor Petrov, and dedicated to all sorts of computations involving root systems, Weyl groups, Bruhat order, etc.
WeylGroups (version 0.1) (right click and "save" on a mac).
You first need a working version of Macaulay 2, available freely from here. Then, the package is installed by the standard procedure: for example, on a unix/linux or a Mac OS X system, lauch M2 from the directory where you have saved the package file, and within M2, type:
installPackage "WeylGroups"
This should install the package and the documentation files. This being done, the package can be loaded by typing:
loadPackage "WeylGroups"
in future M2 sessions.
All functions are documented in the usual Macaulay 2 documentation style and come with examples.
For example, to view the documentation corresponding to the whole package, type help "WeylGroups" or viewHelp "WeylGroups" to open it in your web browser.