#12895: Lookup rules associated with functions/values in GHCI -------------------------------------+------------------------------------- Reporter: harpocrates | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: GHCi | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- It would be nice to have a way to look up in GHCi what rules can fire for a certain constant as the outmost symbol on the LHS. For example, something like {{{ ghci> :pragmas map {-# RULE "map" [~1] forall f xs. map f xs = build (\c n -> foldr (mapFB c f) n xs) #-} {-# RULE "map/coerce" [1] map coerce = coerce #-} }}} As the name suggests, I think we would also want to list applicable NOINLINE, INLINE, INLINABLE, CONLIKE, SPECIALIZE, etc pragmas too. This would simplify the process of debugging mis-firing rules. If this isn't too difficult, I'd love to try implementing it. I've been looking for some way of contributing to GHC. This initially came up here http://stackoverflow.com/q/38651602/3072788. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12895 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler