-editFile str
- | null str = do
- -- find the name of the "topmost" file loaded
- session <- getSession
- graph0 <- io (GHC.getModuleGraph session)
- graph1 <- filterM (io . GHC.isLoaded session . GHC.ms_mod_name) graph0
- let graph2 = flattenSCCs (GHC.topSortModuleGraph True graph1 Nothing)
- case GHC.ml_hs_file (GHC.ms_location (last graph2)) of
- Just file -> do_edit file
- Nothing -> throwDyn (CmdLineError "unknown file name")
- | otherwise = do_edit str
- where
- do_edit file = do
- st <- getGHCiState
- let cmd = editor st
- when (null cmd) $
- throwDyn (CmdLineError "editor not set, use :set editor")
- io $ system (cmd ++ ' ':file)
- return ()
+editFile str =
+ do file <- if null str then chooseEditFile else return str
+ st <- getGHCiState
+ let cmd = editor st
+ when (null cmd)
+ $ throwDyn (CmdLineError "editor not set, use :set editor")
+ io $ system (cmd ++ ' ':file)
+ return ()
+
+-- The user didn't specify a file so we pick one for them.
+-- Our strategy is to pick the first module that failed to load,
+-- or otherwise the first target.
+--
+-- XXX: Can we figure out what happened if the depndecy analysis fails
+-- (e.g., because the porgrammeer mistyped the name of a module)?
+-- XXX: Can we figure out the location of an error to pass to the editor?
+-- XXX: if we could figure out the list of errors that occured during the
+-- last load/reaload, then we could start the editor focused on the first
+-- of those.
+chooseEditFile :: GHCi String
+chooseEditFile =
+ do session <- getSession
+ let hasFailed x = io $ fmap not $ GHC.isLoaded session $ GHC.ms_mod_name x
+
+ graph <- io (GHC.getModuleGraph session)
+ failed_graph <- filterM hasFailed graph
+ let order g = flattenSCCs $ GHC.topSortModuleGraph True g Nothing
+ pick xs = case xs of
+ x : _ -> GHC.ml_hs_file (GHC.ms_location x)
+ _ -> Nothing
+
+ case pick (order failed_graph) of
+ Just file -> return file
+ Nothing ->
+ do targets <- io (GHC.getTargets session)
+ case msum (map fromTarget targets) of
+ Just file -> return file
+ Nothing -> throwDyn (CmdLineError "No files to edit.")
+
+ where fromTarget (GHC.Target (GHC.TargetFile f _) _) = Just f
+ fromTarget _ = Nothing -- when would we get a module target?