Troll: A dice roll language and calculator

Use Troll online!

There is a web interface for Troll.

You can roll dice and calculate probabilities. There are some limitations on probability calculations to avoid stressing the server, so calculations that use a lot of time or memory will abort. This will affect some (but not all) calculations involving many dice or rerolls. If you get into this limitation, you can run Troll on your own computer (by downloading and compiling the sources below), but that will be with a more primitive user interface.

About Troll

I have combined my research into domain-specific languages and my interest in board games and role-playing games to design and implement a language for specifying dice-roll mechanisms.

The first version of the language Roll was released in early 2002 and a paper about the design and implementation was presented at the conference Practical Aspects of Declarative Languages in New Orleans, January 2003. Roll was used to calculate probabilities for several alternative dice-roll mechanisms during the development of the new version of the RPG World of Darkness system from White Wolf.

Based on experiences with Roll, I in 2006 redesigned the language to make it easier to use and added a few new features. The result is Troll, which is the current version.

In Troll, you can write a definition for a dice-roll method like sum largest 3 4d6 (corresponding to a common method for rolling attributes in Dungeons & Dragons) and either get randomly generated results based on this definition or get a probability distribution:

   Value    % =                 % >=              
      3 :    0.0771604938272   100.0               
      4 :    0.308641975309     99.9228395062      
      5 :    0.771604938272     99.6141975309      
      6 :    1.62037037037      98.8425925926      
      7 :    2.93209876543      97.2222222222      
      8 :    4.78395061728      94.2901234568      
      9 :    7.02160493827      89.5061728395      
     10 :    9.41358024691      82.4845679012      
     11 :   11.4197530864       73.0709876543      
     12 :   12.8858024691       61.6512345679      
     13 :   13.2716049383       48.7654320988      
     14 :   12.3456790123       35.4938271605      
     15 :   10.1080246914       23.1481481481      
     16 :    7.25308641975      13.0401234568      
     17 :    4.16666666667       5.78703703704     
     18 :    1.62037037037       1.62037037037     

Average = 12.2445987654    Spread = 2.84684444531  Mean deviation = 2.31853947569

Download Troll

Last update: December 27 2013.

Troll manual

Last update: November 21 2013.

Download code for Troll web interface

Note: Requires ML server pages to run.

Last update: November 21 2013.

Conference paper about Troll

Last update: April 28 2009.

Slides for the conference paper

Last update: April 24 2009.

Article about dice-mechanisms in role-playing games

Last update: May 31 2007.

Download Roll (obsolete)

Windows installer for Moscow ML

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Torben Mogensen
DIKU, University of Copenhagen, Universitetsparken 5, DK-2100 København Ø
E-mail: torbenm@diku.dk Telephone: (+45) 21 84 96 72 Fax: (+45) 35 32 14 01