What is Hayoo?

Hayoo is a search engine for Hackage packages, which allows you to search for functions, data types and packages. Each indexed document consists of a name, a description and, if applicable, a signature. Have a look at the examples on how to use Hayoo. In constrast to Hoogle, all available packages are indexed, but the signature search is not as advanced.


Hayoo uses Hunt for indexing and searching. Hunt is a flexible, lightweight search platform with a powerful query language and JSON API. Hayoo exposes the query language through its own interface and allows the execution of advanced queries.

Additionally, Hunt consists of a standalone web server for easy integration into existing infrastructures without having to write Haskell code.


Hayoo exposes a JSON API for other clients via /json. The page parameter can be used to cycle through the pages.


Any feedback is greatly appreciated! You can contact us via e-mail (hayoo2@fh-wedel.de) or use the issue system to report bugs or suggest features.


The old Hayoo! was based on the Holumbus search engine, which was developed in 2008-2009 by Timo B. Kranz and Sebastian M. Gauck.

The new Hayoo is a rewrite on top of the Hunt search engine, the successor of Holumbus, which was started in 2013 by Ulf Sauer and Chris Reumann to improve and extend the existing Holumbus framework.

Both projects were developed at the FH Wedel under supervision and active support of Prof. Dr. Uwe Schmidt.