Simplify tactics state structure (#1449)

* Store total number of arguments in TopLevelArgPrv

* Re-enable tracing other solutions

* Document a bug I ran into while trying to dogfood

* Replace the janky (Trace,) extract with something more principled

* Add explicit constructors for introducing hypotheses

* Split apart creation of hypothesis from introduction of it

* Produce better debug output for other solns

* Track all the bindings that get generated in Synthesized

* Remove ts_intro_vals; use synthesized bindings instead

* Track used variables in the Synthesis

* Remove a debug trace

* Add some documentation about what's happening here.

* Minor tidying

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

plugins/hls-tactics-plugin/src/Ide/Plugin/Tactic.hs

@@ -23,6 +23,7 @@ import           Data.Aeson
 import           Data.Bifunctor                                   (Bifunctor (bimap))
 import           Data.Bool                                        (bool)
 import           Data.Data                                        (Data)
+import           Data.Foldable (for_)
 import           Data.Generics.Aliases                            (mkQ)
 import           Data.Generics.Schemes                            (everything)
 import           Data.Maybe
@@ -144,6 +145,7 @@ mkWorkspaceEdits
     -> RunTacticResults
     -> Either ResponseError (Maybe WorkspaceEdit)
 mkWorkspaceEdits span dflags ccs uri pm rtr = do
+  for_ (rtr_other_solns rtr) $ traceMX "other solution"
   let g = graftHole (RealSrcSpan span) rtr
       response = transform dflags ccs uri g pm
    in case response of

plugins/hls-tactics-plugin/src/Ide/Plugin/Tactic/CodeGen.hs

@@ -7,14 +7,11 @@ module Ide.Plugin.Tactic.CodeGen
   , module Ide.Plugin.Tactic.CodeGen.Utils
   ) where
 
-import           Control.Lens                    ((%~), (+~), (<>~))
+import           Control.Lens ((+~))
 import           Control.Monad.Except
-import           Control.Monad.State             (MonadState)
-import           Control.Monad.State.Class       (modify)
-import           Data.Generics.Product           (field)
+import           Data.Generics.Product (field)
 import           Data.List
-import qualified Data.Map                        as M
-import qualified Data.Set                        as S
+import qualified Data.Set as S
 import           Data.Traversable
 import           DataCon
 import           Development.IDE.GHC.Compat
@@ -29,32 +26,16 @@ import           Ide.Plugin.Tactic.Judgements
 import           Ide.Plugin.Tactic.Machinery
 import           Ide.Plugin.Tactic.Naming
 import           Ide.Plugin.Tactic.Types
-import           Type                            hiding (Var)
+import           Type hiding (Var)
 
 
-useOccName :: MonadState TacticState m => Judgement -> OccName -> m ()
-useOccName jdg name =
-  -- Only score points if this is in the local hypothesis
-  case M.lookup name $ hyByName $ jLocalHypothesis jdg of
-    Just{}  -> modify
-             $ (withUsedVals $ S.insert name)
-             . (field @"ts_unused_top_vals" %~ S.delete name)
-    Nothing -> pure ()
-
 
 ------------------------------------------------------------------------------
 -- | Doing recursion incurs a small penalty in the score.
 countRecursiveCall :: TacticState -> TacticState
 countRecursiveCall = field @"ts_recursion_count" +~ 1
 
 
-------------------------------------------------------------------------------
--- | Insert some values into the unused top values field. These are
--- subsequently removed via 'useOccName'.
-addUnusedTopVals :: MonadState TacticState m => S.Set OccName -> m ()
-addUnusedTopVals vals = modify $ field @"ts_unused_top_vals" <>~ vals
-
-
 destructMatches
     :: (DataCon -> Judgement -> Rule)
        -- ^ How to construct each match
@@ -63,7 +44,7 @@ destructMatches
     -> CType
        -- ^ Type being destructed
     -> Judgement
-    -> RuleM (Trace, [RawMatch])
+    -> RuleM (Synthesized [RawMatch])
 destructMatches f scrut t jdg = do
   let hy = jEntireHypothesis jdg
       g  = jGoal jdg
@@ -76,16 +57,21 @@ destructMatches f scrut t jdg = do
         _ -> fmap unzipTrace $ for dcs $ \dc -> do
           let args = dataConInstOrigArgTys' dc apps
           names <- mkManyGoodNames (hyNamesInScope hy) args
-          let hy' = zip names $ coerce args
-              j = introducingPat scrut dc hy'
+          let hy' = patternHypothesis scrut dc jdg
+                  $ zip names
+                  $ coerce args
+              j = introduce hy'
                 $ withNewGoal g jdg
-          (tr, sg) <- f dc j
-          modify $ withIntroducedVals $ mappend $ S.fromList names
-          pure ( rose ("match " <> show dc <> " {" <>
+          Synthesized tr sc uv sg <- f dc j
+          pure
+            $ Synthesized
+              ( rose ("match " <> show dc <> " {" <>
                           intercalate ", " (fmap show names) <> "}")
-                    $ pure tr
-               , match [mkDestructPat dc names] $ unLoc sg
-               )
+                    $ pure tr)
+              (sc <> hy')
+              uv
+            $ match [mkDestructPat dc names]
+            $ unLoc sg
 
 
 ------------------------------------------------------------------------------
@@ -114,10 +100,8 @@ infixifyPatIfNecessary dcon x
 
 
 
-unzipTrace :: [(Trace, a)] -> (Trace, [a])
-unzipTrace l =
-  let (trs, as) = unzip l
-   in (rose mempty trs, as)
+unzipTrace :: [Synthesized a] -> Synthesized [a]
+unzipTrace = sequenceA
 
 
 -- | Essentially same as 'dataConInstOrigArgTys' in GHC,
@@ -154,16 +138,19 @@ destruct' :: (DataCon -> Judgement -> Rule) -> HyInfo CType -> Judgement -> Rule
 destruct' f hi jdg = do
   when (isDestructBlacklisted jdg) $ throwError NoApplicableTactic
   let term = hi_name hi
-  useOccName jdg term
-  (tr, ms)
+  Synthesized tr sc uv ms
       <- destructMatches
            f
            (Just term)
            (hi_type hi)
            $ disallowing AlreadyDestructed [term] jdg
-  pure ( rose ("destruct " <> show term) $ pure tr
-       , noLoc $ case' (var' term) ms
-       )
+  pure
+    $ Synthesized
+        (rose ("destruct " <> show term) $ pure tr)
+        sc
+        (S.insert term uv)
+    $ noLoc
+    $ case' (var' term) ms
 
 
 ------------------------------------------------------------------------------
@@ -186,10 +173,10 @@ buildDataCon
     :: Judgement
     -> DataCon            -- ^ The data con to build
     -> [Type]             -- ^ Type arguments for the data con
-    -> RuleM (Trace, LHsExpr GhcPs)
+    -> RuleM (Synthesized (LHsExpr GhcPs))
 buildDataCon jdg dc tyapps = do
   let args = dataConInstOrigArgTys' dc tyapps
-  (tr, sgs)
+  Synthesized tr sc uv sgs
       <- fmap unzipTrace
        $ traverse ( \(arg, n) ->
                     newSubgoal
@@ -199,6 +186,6 @@ buildDataCon jdg dc tyapps = do
                   $ CType arg
                   ) $ zip args [0..]
   pure
-    . (rose (show dc) $ pure tr,)
+    $ Synthesized (rose (show dc) $ pure tr) sc uv
     $ mkCon dc sgs
 

plugins/hls-tactics-plugin/src/Ide/Plugin/Tactic/Judgements.hs

@@ -1,33 +1,7 @@
 {-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE ViewPatterns     #-}
 
-module Ide.Plugin.Tactic.Judgements
-  ( blacklistingDestruct
-  , unwhitelistingSplit
-  , introducingLambda
-  , introducingRecursively
-  , introducingPat
-  , jGoal
-  , jHypothesis
-  , jEntireHypothesis
-  , jPatHypothesis
-  , substJdg
-  , unsetIsTopHole
-  , filterSameTypeFromOtherPositions
-  , isDestructBlacklisted
-  , withNewGoal
-  , jLocalHypothesis
-  , isSplitWhitelisted
-  , isPatternMatch
-  , filterPosition
-  , isTopHole
-  , disallowing
-  , mkFirstJudgement
-  , hypothesisFromBindings
-  , isTopLevel
-  , hyNamesInScope
-  , hyByName
-  ) where
+module Ide.Plugin.Tactic.Judgements where
 
 import           Control.Arrow
 import           Control.Lens                        hiding (Context)
@@ -89,35 +63,39 @@ withNewGoal :: a -> Judgement' a -> Judgement' a
 withNewGoal t = field @"_jGoal" .~ t
 
 
+introduce :: Hypothesis a -> Judgement' a -> Judgement' a
+introduce hy = field @"_jHypothesis" <>~ hy
+
+
 ------------------------------------------------------------------------------
 -- | Helper function for implementing functions which introduce new hypotheses.
-introducing
-    :: (Int -> Provenance)  -- ^ A function from the position of the arg to its
-                            -- provenance.
+introduceHypothesis
+    :: (Int -> Int -> Provenance)
+        -- ^ A function from the total number of args and position of this arg
+        -- to its provenance.
     -> [(OccName, a)]
-    -> Judgement' a
-    -> Judgement' a
-introducing f ns =
-  field @"_jHypothesis" <>~ (Hypothesis $ zip [0..] ns <&>
-    \(pos, (name, ty)) -> HyInfo name (f pos) ty)
+    -> Hypothesis a
+introduceHypothesis f ns =
+  Hypothesis $ zip [0..] ns <&> \(pos, (name, ty)) ->
+    HyInfo name (f (length ns) pos) ty
 
 
 ------------------------------------------------------------------------------
 -- | Introduce bindings in the context of a lamba.
-introducingLambda
+lambdaHypothesis
     :: Maybe OccName   -- ^ The name of the top level function. For any other
                        -- function, this should be 'Nothing'.
     -> [(OccName, a)]
-    -> Judgement' a
-    -> Judgement' a
-introducingLambda func = introducing $ \pos ->
-  maybe UserPrv (\x -> TopLevelArgPrv x pos) func
+    -> Hypothesis a
+lambdaHypothesis func =
+  introduceHypothesis $ \count pos ->
+    maybe UserPrv (\x -> TopLevelArgPrv x pos count) func
 
 
 ------------------------------------------------------------------------------
 -- | Introduce a binding in a recursive context.
-introducingRecursively :: [(OccName, a)] -> Judgement' a -> Judgement' a
-introducingRecursively = introducing $ const RecursivePrv
+recursiveHypothesis :: [(OccName, a)] -> Hypothesis a
+recursiveHypothesis = introduceHypothesis $ const $ const RecursivePrv
 
 
 ------------------------------------------------------------------------------
@@ -176,7 +154,7 @@ findPositionVal jdg defn pos = listToMaybe $ do
   -- ancstry through potentially disallowed terms in the hypothesis.
   (name, hi) <- M.toList $ M.map (overProvenance expandDisallowed) $ hyByName $ jEntireHypothesis jdg
   case hi_provenance hi of
-    TopLevelArgPrv defn' pos'
+    TopLevelArgPrv defn' pos' _
       | defn == defn'
       , pos  == pos' -> pure name
     PatternMatchPrv pv
@@ -243,26 +221,22 @@ extremelyStupid__definingFunction =
   fst . head . ctxDefiningFuncs
 
 
-------------------------------------------------------------------------------
--- | Pattern vals are currently tracked in jHypothesis, with an extra piece of
--- data sitting around in jPatternVals.
-introducingPat
+patternHypothesis
     :: Maybe OccName
     -> DataCon
-    -> [(OccName, a)]
     -> Judgement' a
-    -> Judgement' a
-introducingPat scrutinee dc ns jdg
-  = introducing (\pos ->
+    -> [(OccName, a)]
+    -> Hypothesis a
+patternHypothesis scrutinee dc jdg
+  = introduceHypothesis $ \_ pos ->
       PatternMatchPrv $
         PatVal
-          scrutinee
-          (maybe mempty
-                (\scrut -> S.singleton scrut <> getAncestry jdg scrut)
-                scrutinee)
-          (Uniquely dc)
-          pos
-    ) ns jdg
+            scrutinee
+            (maybe mempty
+                  (\scrut -> S.singleton scrut <> getAncestry jdg scrut)
+                  scrutinee)
+            (Uniquely dc)
+            pos
 
 
 ------------------------------------------------------------------------------

plugins/hls-tactics-plugin/src/Ide/Plugin/Tactic/KnownStrategies/QuickCheck.hs

@@ -44,8 +44,13 @@ deriveArbitrary = do
             terminal_expr = mkVal "terminal"
             oneof_expr = mkVal "oneof"
         pure
-          ( tracePrim "deriveArbitrary"
-          , noLoc $
+          $ Synthesized (tracePrim "deriveArbitrary")
+              -- TODO(sandy): This thing is not actually empty! We produced
+              -- a bespoke binding "terminal", and a not-so-bespoke "n".
+              -- But maybe it's fine for known rules?
+              mempty
+              mempty
+          $ noLoc $
               let' [valBind (fromString "terminal") $ list $ fmap genExpr terminal] $
                 appDollar (mkFunc "sized") $ lambda [bvar' (mkVarOcc "n")] $
                   case' (infixCall "<=" (mkVal "n") (int 1))
@@ -57,7 +62,6 @@ deriveArbitrary = do
                             (list $ fmap genExpr big)
                             terminal_expr
                     ]
-          )
     _ -> throwError $ GoalMismatch "deriveArbitrary" ty
 
 

plugins/hls-tactics-plugin/src/Ide/Plugin/Tactic/LanguageServer.hs

@@ -197,7 +197,8 @@ getRhsPosVals rss tcs
         , isHole $ occName hole  -- and the span is a hole
         -> First $ do
             patnames <- traverse getPatName ps
-            pure $ zip patnames $ [0..] <&> TopLevelArgPrv name
+            pure $ zip patnames $ [0..] <&> \n ->
+              TopLevelArgPrv name n (length patnames)
       _ -> mempty
   ) tcs