Hi Haskell, This is the first release of Dr Haskell, a tool to help suggest improvements to your code. GETTING DR HASKELL See http://www-users.cs.york.ac.uk/~ndm/projects/drhaskell.php for details on how to download and install the program. There are prebuilt Windows binaries. This project requires Yhc to be installed and working, of which there are also prebuilt binaries (see the above web page for pointers). This program should work fine on Linux/Mac etc, provided you first have Yhc installed. AN EXAMPLE SESSION Imagine you have a program, and somewhere deep inside the program it has the expression: take 5 (repeat '!') An experienced Haskell user might realise that this is in fact replicate, but a beginner has no way of discovering this function for themselves, besides reading the standard libraries! Put that definition in a Haskell source file, say Test.hs, then run:
drhaskell Test.hs I can apply use_replicate in check_elem (5:10-6:80)
Dr Haskell gives a suggestion (use_replicate) to a specific function (check_elem) and a given source location (line 5, column 10) Of course, they might have written take 5 $ repeat '!', or take n . repeat, or quite a few other variations. Dr Haskell can see through these things nicely. Of course, Dr Haskell can make more powerful suggestions, for example: if f x then 4 else if g x then 4 else primes !! 10 And Dr Haskell will suggest you use f x || g x instead The hints are isolated from the program, and can be easily changed by the user. More hint patches are most welcome. See http://www.cs.york.ac.uk/fp/darcs/drhaskell/Hints.hs for a list of the hints currently available in the code. LIMITATIONS Requires a working copy of Yhc. You must first have your program/file successfully compiling with Yhc. Once you have got over the admin side (compiling etc, invoking correctly), the actual hint algorithm is pretty robust. Bug reports/suggestions/patches most welcome. YHC INFORMATION Home page: http://haskell.org/haskellwiki/Yhc Build details: http://haskell.org/haskellwiki/Yhc/Building Windows snapshot: http://haskell.org/haskellwiki/Yhc/Snapshots If Yhc won't build for you, or you have other difficulties, please bug the Yhc Team on their mailing list, yhc -at- haskell -dot- org. Thanks Neil