You might need to enable optimization for RULES to get picked up at all. On Thu, Apr 11, 2019 at 11:03 PM Bill Hallahan wrote:

Hi,

I'm trying to use the GHC API (8.2.2) to extract the rewrite rules from a module, but have run into some difficulties. I've written the following code (all code is also attached as files):

module Main where

import GHC import GHC.Paths import HscTypes

main :: IO () main = do loadProj "Test.hs"

loadProj :: FilePath -> IO () loadProj src = do modgutss <- runGhc (Just libdir) $ do flags <- getSessionDynFlags _ <- setSessionDynFlags flags

target <- guessTarget src Nothing _ <- setTargets [target] _ <- load LoadAllTargets

mod_graph <- getModuleGraph parsed_mods <- mapM parseModule mod_graph typed_mods <- mapM typecheckModule parsed_mods desug_mods <- mapM desugarModule typed_mods

return $ map coreModule desug_mods

let rules = map (\mg -> ( moduleNameString . moduleName $ mg_module mg , length $ mg_rules mg) ) modgutss print $ rules

return ()

It loads Test.hs (see below my signature) which contains a single rewrite rule. Then, it obtains the ModGuts, and prints a tuple of the name of the module, and the length of the rule list. I would expect this to be ("Test", 1), but, in fact, what gets printed is ("Test", 0). For some reason, the ModGuts does not have the rewrite rule from the file.

I'm guessing I'm misunderstanding something about how the GHC API works. If anyone has any advice about how to fix this code to load rewrite rules (or even where to begin looking) I would appreciate it!

Thanks, Bill Hallahan

Test.hs: module Test where

import Prelude hiding (map)

map :: (a -> b) -> [a] -> [b] map f (x:xs) = f x:map f xs map _ [] = [] {-# NOINLINE [0] map #-}

{-# RULES "map/map" forall f g xs . map f (map g xs) = map (f . g) xs #-} _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs

-- brandon s allbery kf8nh allbery.b@gmail.com

Hi Bill, You may try to set the DynFlag Opt_IgnoreInterfacePragmas to False. If set to True,, which is the default, GHC doesn't load a lot of optimization stuff. Good luck and kind regards Roland Am Donnerstag, den 11.04.2019, 23:02 -0400 schrieb Bill Hallahan:

Hi,

I'm trying to use the GHC API (8.2.2) to extract the rewrite rules from a module, but have run into some difficulties.  I've written the following code (all code is also attached as files):

    module Main where

    import GHC     import GHC.Paths     import HscTypes

    main :: IO ()     main = do         loadProj "Test.hs"

    loadProj :: FilePath -> IO ()     loadProj src = do         modgutss <- runGhc (Just libdir) $ do             flags <- getSessionDynFlags             _ <- setSessionDynFlags flags

            target <- guessTarget src Nothing             _ <- setTargets [target]             _ <- load LoadAllTargets                          mod_graph <- getModuleGraph             parsed_mods <- mapM parseModule mod_graph             typed_mods <- mapM typecheckModule parsed_mods             desug_mods <- mapM desugarModule typed_mods

            return $ map coreModule desug_mods

        let rules = map (\mg -> ( moduleNameString . moduleName $ mg_module mg                                 , length $ mg_rules mg)                         ) modgutss         print $ rules

        return ()

It loads Test.hs (see below my signature) which contains a single rewrite rule.  Then, it obtains the ModGuts, and prints a tuple of the name of the module, and the length of the rule list.  I would expect this to be ("Test", 1), but, in fact, what gets printed is ("Test", 0).  For some reason, the ModGuts does not have the rewrite rule from the file.

I'm guessing I'm misunderstanding something about how the GHC API works.  If anyone has any advice about how to fix this code to load rewrite rules (or even where to begin looking) I would appreciate it!

Thanks, Bill Hallahan

Test.hs:     module Test where

    import Prelude hiding (map)

    map :: (a -> b) -> [a] -> [b]     map f (x:xs) = f x:map f xs     map _ [] = []     {-# NOINLINE [0] map #-}

    {-# RULES      "map/map"   forall f g xs . map f (map g xs) = map (f . g) xs       #-} _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs