Hi, I went looking for the the function in Haskell to calculate cos^{-1}, inverse cosine. Unfortunately, the poor documentation in the libraries hampered my attempts. The documentation for the trig functions in Haskell is completely non-existent: http://haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html#v%3Acos For a start, its probably a good idea to mention that cos is an abbreviation of cosine (most people will know, but its handy to state it). Secondly, and much more importantly, it should state whether these measurements are in degrees or radians. It should also state things like acos is the inverse of cos - its been a while since I last used trig and I had to look it up!!! We are also lacking documentation for things like odd/even, which are obvious enough, but its nice to say that they meet the intuition. Could haddock be extended to give a warning message (in -Wall mode perhaps) when an exported function has no comment associated with it? This would be a really nice project for someone to take on, and very much appreciated :-) Thanks Neil