GSoC Hoogle: Week 10

This week I've been in Bristol, and am just about to head off to the Harbour Festival. Next week I'm heading off to AngloHaskell 2008, and will be talking about Hoogle type searching on the Saturday.

This week has been type search, yet again. There were issues with algorithmic complexity, combinatorial explosions and other fun stuff. However, its now finished. The type search is now fast enough (you can run Hoogle in Hugs against the core libraries) and gives good results. Rather than describe type searching, its easier to give an example. Searching for (a -> b) -> [a] -> [b] in Hoogle 3 gives:

Prelude.map :: (a -> b) -> [a] -> [b]
Data.List.map :: (a -> b) -> [a] -> [b]
Control.Parallel.S... parMap :: Strategy b -> (a -> b) -> [a] -> [b]
Prelude.scanr :: (a -> b -> b) -> b -> [a] -> [b]
Data.List.scanr :: (a -> b -> b) -> b -> [a] -> [b]
Prelude.scanl :: (a -> b -> a) -> a -> [b] -> [a]
Data.List.scanl :: (a -> b -> a) -> a -> [b] -> [a]
Prelude.concatMap :: (a -> [b]) -> [a] -> [b]

But in Hoogle 4 gives:

Prelude map :: (a -> b) -> [a] -> [b]
Data.List map :: (a -> b) -> [a] -> [b]
Prelude fmap :: Functor f => (a -> b) -> f a -> f b
Control.Applicative <$> :: Functor f => (a -> b) -> f a -> f b
Control.Monad fmap :: Functor f => (a -> b) -> f a -> f b
Control.Monad.Instances fmap :: Functor f => (a -> b) -> f a -> f b
Control.Applicative liftA :: Applicative f => (a -> b) -> f a -> f b
Data.Traversable fmapDefault :: Traversable t => (a -> b) -> t a -> t b
Control.Monad liftM :: Monad m => (a1 -> r) -> m a1 -> m r
Control.Parallel.Strategies parMap :: Strategy b -> (a -> b) -> [a] -> [b]

I think the new results are better. For more details, come to the AngloHaskell talk.

Next Week: I want to release a public beta of Hoogle 4 in command line form. I want to start on the web search engine and tweak the ranking algorithm. I'll also be writing up type search in the form of a presentation.

User Visible Changes: Type search works well and fast.