A list of usecases that codesearch.aelve.com aims to support.

Works

• Somebody on the internet wants to know (more-or-less just for fun, apparently) if anybody uses the rare coelgot function.
• The OEH constructor in a family of libraries (stompl, stomp-queue, etc) allows setting up an error handler for STOMP connections, but I want to see what's the exact logic for handling it. (Note: would be nicer if it was possible to specify a pattern for library names to match.)
• I run a software consultancy and one of my clients wonders what libraries Haskell has that can can work with certificate requests (CSRs). A search by some common string constants found in CSRs works pretty well.
• I get a mysterious error saying read-loop: AsyncCancelled; there is no read-loop string anywhere in my code, so where does it come from? If I know what dependency contains this string, I can find the bug.
• I'm preparing a talk about the -XOverloadedLabels extension and I want to find all Haskell libraries that use it.
• I want to find a Haskell library that can create a Basic HTTP auth header from a login/pass – for that I search for modules that mention "Basic ".
• I want to find all uses of buggy joinWith from Data.ByteString.Base64. (Update: it's not buggy anymore.)
• Out of curiosity, I want to see how many people use anything other than first and second from Control.Arrow.
• I'm doing research for my talk and I need to know: are there any libraries that implement anonymous records with FromJSON instances? Just searching for KnownSymbol results in too many false positives.
• Find all uses of throw in a family of libraries to see what exceptions those libraries can throw (and therefore I, the library user, have to handle).
• I want to find a JSON parser that uses Megaparsec because then I would be able to integrate it into my own Megaparsec parser.
• I want to find all infix declarations for non-operators in lens to port them to microlens. Search.
• Is per taken as a function name?
• Neil Mitchell wanted to know which functions from the Hlint API are used in the wild: https://neilmitchell.blogspot.com/2019/06/hlints-path-to-ghc-parser.html

Doesn't work yet

• I want to find out all the different ways in which people import qualified Data.Text and see statistics on that, in order to understand what style is the most common in the community (then I can just follow it instead of having to argue about what style is "better").

  Requires: statistics by match groups

• I want to find all uses of <$> in Haddock that are not escaped properly (i.e. not '<$>') to assess how widespread the problem is.

  Requires: knowledge of context (are we inside of a comment or outside?)

• I want to see if anyone still uses the deprecated NPlusKPatterns language extension.

  Requires: multiline search (without it I can't specify a pattern like "inside a LANGUAGE pragma", because they can be multiline)