The Functional Rent Advisor

The Functional Rent Advisor (FRA) is an intelligent Internet application that allows calculating an estimate of the fair rent for a flat in Munich. The FRA is the electronic version of the "Mietspiegel" (MS) which is published regularly by the City of Munich.

All relevant information for calculating an estimated rent will be collected in a questionnaire. The users need to fill in only what they know and what they care about. All answers are optional. There are only four questions requiring numeric inputs, where it is possible to give a range and one question about location requiring a search in a list of districts. Optional detailed questions are provided to calculate the fixed costs where numeric input can be given. Usually, the user will just ignore this section and thus a range from minimal to maximal fixed costs will be added to the estimated rent.

The FRA is a re-implementation of the Munich Rent Advisor using the high-level purely functional language Haskell.

• The correspondence between the "paper version" (MS) and the code is much closer than in its Prolog precursor.
• Being a strongly typed language with an advanced type system and powerful abstraction facilities due to modules and higher-order functions, Haskell supports software engineering principles better than Prolog does.
• A convenient library for HTML generation and CGI scripting. This relieves one from the error-prone tasks of generating correct HTML and handling of the HTTP protocol.

Rent Calculation

Paper (gzipped PostScript, 124kB) describing the implementation.

The Functional Rent Advisor is available in German and English. The version you get is chosen according to your preferred language. To choose your prefered language, set the language preferences of your browser appropriately.

Authors: Slim Abdennadher, Tim Geisler and Sven Panne