[Haskell-cafe] find functions that produce / consume a type?

[Eric Seidel]

Hoogle does let you restrict the search to the output type by prefixing your query with “::”. For example, “:: Maybe a” produces a list of functions that return a Maybe. 

https://www.haskell.org/hoogle/?hoogle=%3A%3A+Maybe+a

Unfortunately this doesn’t seem to work in the new Hoogle hosted at hoogle.haskell.org. 

Sent from my iPhone

> On Nov 9, 2018, at 04:59, Johannes Waldmann <johannes.waldmann at htwk-leipzig.de> wrote:
> 
> Dear Cafe,
> 
> can we automate something like the following
> 
>  for any type  T  that appears in signatures (shown by haddock),
>  add (separate) lists of "functions that produce T",
>  "functions that consume T".
> 
> Hoogle can type-search approximately, but
> * it would always (want to) match the full type AST
> (matching with a subtree incurs a penalty?),
> * and not distinguish between producer and consumer?
> 
> E.g.,
> https://ndmitchell.com/downloads/slides-hoogle_finding_functions_from_types-16_may_2011.pdf
> Slide #29 "Per Argument Searching"
> uses "search arguments", "search results" -
> only to  merge the results immediately.
> Can we keep them separate?
> 
> - J.W.
> 
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