[Haskell-cafe] Hoogle vs Hayoo

Johannes Waldmann waldmann at imn.htwk-leipzig.de
Fri Aug 23 09:35:23 CEST 2013

Mateusz Kowalczyk <fuuzetsu <at> fuuzetsu.co.uk> writes:

> I always thought [hayoo] was just Hoogle with more indexed docs.

Wait - there's a semantic difference:

hoogle does understand type signatures
(e.g., it can specialize them, or flip arguments of functions)
while hayoo just treats signatures as strings (it seems).

Example: search for [a] -> [a] 

hoogle: will also return  Data.Text.transpose :: [Text] -> [Text]
(note: instantiated  a  to Text)

hayoo: will also return Data.List.isInfixOf :: [a] -> [a] -> Bool
(note:  the type is [a] -> ([a] -> Bool), 
so it does actually not contain the type from the query)

I much prefer hoogle's query semantics.

- J.W.

PS: but hoogle also returns   inits :: [a] -> [[a]]
which is not an instance of the query. Why is this?

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