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

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-... Slide #29 "Per Argument Searching" uses "search arguments", "search results" - only to merge the results immediately. Can we keep them separate? - J.W.