{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE RankNTypes #-}
module Wingman.Machinery where
import Control.Applicative (empty)
import Control.Concurrent.Chan.Unagi.NoBlocking (newChan, writeChan, OutChan, tryRead, tryReadChan)
import Control.Lens ((<>~))
import Control.Monad.Reader
import Control.Monad.State.Class (gets, modify, MonadState)
import Control.Monad.State.Strict (StateT (..), execStateT)
import Control.Monad.Trans.Maybe
import Data.Coerce
import Data.Foldable
import Data.Functor ((<&>))
import Data.Generics (everything, gcount, mkQ)
import Data.Generics.Product (field')
import Data.List (sortBy)
import qualified Data.Map as M
import Data.Maybe (mapMaybe, isJust)
import Data.Monoid (getSum)
import Data.Ord (Down (..), comparing)
import qualified Data.Set as S
import Data.Traversable (for)
import Development.IDE.Core.Compile (lookupName)
import Development.IDE.GHC.Compat hiding (isTopLevel, empty)
import Refinery.Future
import Refinery.ProofState
import Refinery.Tactic
import Refinery.Tactic.Internal
import System.Timeout (timeout)
import Wingman.Context (getInstance)
import Wingman.GHC (tryUnifyUnivarsButNotSkolems, updateSubst, tacticsGetDataCons, freshTyvars)
import Wingman.Judgements
import Wingman.Simplify (simplify)
import Wingman.Types
substCTy :: TCvSubst -> CType -> CType
substCTy subst = coerce . substTy subst . coerce
getSubstForJudgement
:: MonadState TacticState m
=> Judgement
-> m TCvSubst
getSubstForJudgement j = do
-- NOTE(sandy): It's OK to use mempty here, because coercions _can_ give us
-- substitutions for skolems.
let coercions = j_coercion j
unifier <- gets ts_unifier
pure $ unionTCvSubst unifier coercions
------------------------------------------------------------------------------
-- | Produce a subgoal that must be solved before we can solve the original
-- goal.
newSubgoal
:: Judgement
-> Rule
newSubgoal j = do
ctx <- ask
unifier <- getSubstForJudgement j
subgoal
$ normalizeJudgement ctx
$ substJdg unifier
$ unsetIsTopHole
$ normalizeJudgement ctx j
tacticToRule :: Judgement -> TacticsM () -> Rule
tacticToRule jdg (TacticT tt) = RuleT $ flip execStateT jdg tt >>= flip Subgoal Axiom
consumeChan :: OutChan (Maybe a) -> IO [a]
consumeChan chan = do
tryReadChan chan >>= tryRead >>= \case
Nothing -> pure []
Just (Just a) -> (:) <$> pure a <*> consumeChan chan
Just Nothing -> pure []
------------------------------------------------------------------------------
-- | Attempt to generate a term of the right type using in-scope bindings, and
-- a given tactic.
runTactic
:: Int -- ^ Timeout
-> Context
-> Judgement
-> TacticsM () -- ^ Tactic to use
-> IO (Either [TacticError] RunTacticResults)
runTactic duration ctx jdg t = do
let skolems = S.fromList
$ foldMap (tyCoVarsOfTypeWellScoped . unCType)
$ (:) (jGoal jdg)
$ fmap hi_type
$ toList
$ hyByName
$ jHypothesis jdg
tacticState =
defaultTacticState
{ ts_skolems = skolems
}
let stream = hoistListT (flip runReaderT ctx . unExtractM)
$ runStreamingTacticT t jdg tacticState
(in_proofs, out_proofs) <- newChan
(in_errs, out_errs) <- newChan
timed_out <-
fmap (not. isJust) $ timeout duration $ consume stream $ \case
Left err -> writeChan in_errs $ Just err
Right proof -> writeChan in_proofs $ Just proof
writeChan in_proofs Nothing
solns <- consumeChan out_proofs
let sorted =
flip sortBy solns $ comparing $ \(Proof ext _ holes) ->
Down $ scoreSolution ext jdg $ fmap snd holes
case sorted of
((Proof syn _ subgoals) : _) ->
pure $ Right $
RunTacticResults
{ rtr_trace = syn_trace syn
, rtr_extract = simplify $ syn_val syn
, rtr_subgoals = fmap snd subgoals
, rtr_other_solns = reverse . fmap pf_extract $ sorted
, rtr_jdg = jdg
, rtr_ctx = ctx
, rtr_timed_out = timed_out
}
_ -> fmap Left $ consumeChan out_errs
tracePrim :: String -> Trace
tracePrim = flip rose []
------------------------------------------------------------------------------
-- | Mark that a tactic used the given string in its extract derivation. Mainly
-- used for debugging the search when things go terribly wrong.
tracing
:: Functor m
=> String
-> TacticT jdg (Synthesized ext) err s m a
-> TacticT jdg (Synthesized ext) err s m a
tracing s = mappingExtract (mapTrace $ rose s . pure)
------------------------------------------------------------------------------
-- | Mark that a tactic performed recursion. Doing so incurs a small penalty in
-- the score.
markRecursion
:: Functor m
=> TacticT jdg (Synthesized ext) err s m a
-> TacticT jdg (Synthesized ext) err s m a
markRecursion = mappingExtract (field' @"syn_recursion_count" <>~ 1)
------------------------------------------------------------------------------
-- | Map a function over the extract created by a tactic.
mappingExtract
:: Functor m
=> (ext -> ext)
-> TacticT jdg ext err s m a
-> TacticT jdg ext err s m a
mappingExtract f (TacticT m)
= TacticT $ StateT $ \jdg ->
mapExtract id f $ runStateT m jdg
------------------------------------------------------------------------------
-- | Given the results of running a tactic, score the solutions by
-- desirability.
--
-- NOTE: This function is completely unprincipled and was just hacked together
-- to produce the right test results.
scoreSolution
:: Synthesized (LHsExpr GhcPs)
-> Judgement
-> [Judgement]
-> ( Penalize Int -- number of holes
, Reward Bool -- all bindings used
, Penalize Int -- unused top-level bindings
, Penalize Int -- number of introduced bindings
, Reward Int -- number used bindings
, Penalize Int -- number of recursive calls
, Penalize Int -- size of extract
)
scoreSolution ext goal holes
= ( Penalize $ length holes
, Reward $ S.null $ intro_vals S.\\ used_vals
, Penalize $ S.size unused_top_vals
, Penalize $ S.size intro_vals
, Reward $ S.size used_vals + length used_user_vals
, Penalize $ getSum $ syn_recursion_count ext
, Penalize $ solutionSize $ syn_val ext
)
where
initial_scope = hyByName $ jEntireHypothesis goal
intro_vals = M.keysSet $ hyByName $ syn_scoped ext
used_vals = S.intersection intro_vals $ syn_used_vals ext
used_user_vals = filter (isLocalHypothesis . hi_provenance)
$ mapMaybe (flip M.lookup initial_scope)
$ S.toList
$ syn_used_vals ext
top_vals = S.fromList
. fmap hi_name
. filter (isTopLevel . hi_provenance)
. unHypothesis
$ syn_scoped ext
unused_top_vals = top_vals S.\\ used_vals
------------------------------------------------------------------------------
-- | Compute the number of 'LHsExpr' nodes; used as a rough metric for code
-- size.
solutionSize :: LHsExpr GhcPs -> Int
solutionSize = everything (+) $ gcount $ mkQ False $ \case
(_ :: LHsExpr GhcPs) -> True
newtype Penalize a = Penalize a
deriving (Eq, Ord, Show) via (Down a)
newtype Reward a = Reward a
deriving (Eq, Ord, Show) via a
------------------------------------------------------------------------------
-- | Generate a unique unification variable.
newUnivar :: MonadState TacticState m => m Type
newUnivar = do
freshTyvars $
mkInfForAllTys [alphaTyVar] alphaTy
------------------------------------------------------------------------------
-- | Attempt to unify two types.
unify :: CType -- ^ The goal type
-> CType -- ^ The type we are trying unify the goal type with
-> RuleM ()
unify goal inst = do
skolems <- gets ts_skolems
case tryUnifyUnivarsButNotSkolems skolems goal inst of
Just subst ->
modify $ updateSubst subst
Nothing -> cut
cut :: RuleT jdg ext err s m a
cut = RuleT Empty
------------------------------------------------------------------------------
-- | Attempt to unify two types.
canUnify
:: MonadState TacticState m
=> CType -- ^ The goal type
-> CType -- ^ The type we are trying unify the goal type with
-> m Bool
canUnify goal inst = do
skolems <- gets ts_skolems
case tryUnifyUnivarsButNotSkolems skolems goal inst of
Just _ -> pure True
Nothing -> pure False
------------------------------------------------------------------------------
-- | Prefer the first tactic to the second, if the bool is true. Otherwise, just run the second tactic.
--
-- This is useful when you have a clever pruning solution that isn't always
-- applicable.
attemptWhen :: TacticsM a -> TacticsM a -> Bool -> TacticsM a
attemptWhen _ t2 False = t2
attemptWhen t1 t2 True = commit t1 t2
------------------------------------------------------------------------------
-- | Run the given tactic iff the current hole contains no univars. Skolems and
-- already decided univars are OK though.
requireConcreteHole :: TacticsM a -> TacticsM a
requireConcreteHole m = do
jdg <- goal
skolems <- gets ts_skolems
let vars = S.fromList $ tyCoVarsOfTypeWellScoped $ unCType $ jGoal jdg
case S.size $ vars S.\\ skolems of
0 -> m
_ -> failure TooPolymorphic
------------------------------------------------------------------------------
-- | The 'try' that comes in refinery 0.3 causes unnecessary backtracking and
-- balloons the search space. This thing just tries it, but doesn't backtrack
-- if it fails.
--
-- NOTE(sandy): But there's a bug! Or at least, something not understood here.
-- Using this everywhere breaks te tests, and neither I nor TOTBWF are sure
-- why. Prefer 'try' if you can, and only try this as a last resort.
--
-- TODO(sandy): Remove this when we upgrade to 0.4
try'
:: Functor m
=> TacticT jdg ext err s m ()
-> TacticT jdg ext err s m ()
try' t = commit t $ pure ()
------------------------------------------------------------------------------
-- | Sorry leaves a hole in its extract
exact :: HsExpr GhcPs -> TacticsM ()
exact = rule . const . pure . pure . noLoc
------------------------------------------------------------------------------
-- | Lift a function over 'HyInfo's to one that takes an 'OccName' and tries to
-- look it up in the hypothesis.
useNameFromHypothesis :: (HyInfo CType -> TacticsM a) -> OccName -> TacticsM a
useNameFromHypothesis f name = do
hy <- jHypothesis <$> goal
case M.lookup name $ hyByName hy of
Just hi -> f hi
Nothing -> failure $ NotInScope name
------------------------------------------------------------------------------
-- | Lift a function over 'HyInfo's to one that takes an 'OccName' and tries to
-- look it up in the hypothesis.
useNameFromContext :: (HyInfo CType -> TacticsM a) -> OccName -> TacticsM a
useNameFromContext f name = do
lookupNameInContext name >>= \case
Just ty -> f $ createImportedHyInfo name ty
Nothing -> failure $ NotInScope name
------------------------------------------------------------------------------
-- | Find the type of an 'OccName' that is defined in the current module.
lookupNameInContext :: MonadReader Context m => OccName -> m (Maybe CType)
lookupNameInContext name = do
ctx <- asks ctxModuleFuncs
pure $ case find ((== name) . fst) ctx of
Just (_, ty) -> pure ty
Nothing -> empty
getDefiningType
:: TacticsM CType
getDefiningType = do
calling_fun_name <- fst . head <$> asks ctxDefiningFuncs
maybe
(failure $ NotInScope calling_fun_name)
pure
=<< lookupNameInContext calling_fun_name
------------------------------------------------------------------------------
-- | Build a 'HyInfo' for an imported term.
createImportedHyInfo :: OccName -> CType -> HyInfo CType
createImportedHyInfo on ty = HyInfo
{ hi_name = on
, hi_provenance = ImportPrv
, hi_type = ty
}
getTyThing
:: OccName
-> TacticsM (Maybe TyThing)
getTyThing occ = do
ctx <- ask
case lookupOccEnv (ctx_occEnv ctx) occ of
Just (elt : _) -> do
mvar <- lift
$ ExtractM
$ lift
$ lookupName (ctx_hscEnv ctx) (ctx_module ctx)
$ gre_name elt
pure mvar
_ -> pure Nothing
------------------------------------------------------------------------------
-- | Like 'getTyThing' but specialized to classes.
knownClass :: OccName -> TacticsM (Maybe Class)
knownClass occ =
getTyThing occ <&> \case
Just (ATyCon tc) -> tyConClass_maybe tc
_ -> Nothing
------------------------------------------------------------------------------
-- | Like 'getInstance', but uses a class that it just looked up.
getKnownInstance :: OccName -> [Type] -> TacticsM (Maybe (Class, PredType))
getKnownInstance f tys = runMaybeT $ do
cls <- MaybeT $ knownClass f
MaybeT $ getInstance cls tys
------------------------------------------------------------------------------
-- | Lookup the type of any 'OccName' that was imported. Necessarily done in
-- IO, so we only expose this functionality to the parser. Internal Haskell
-- code that wants to lookup terms should do it via 'KnownThings'.
getOccNameType
:: OccName
-> TacticsM Type
getOccNameType occ = do
getTyThing occ >>= \case
Just (AnId v) -> pure $ varType v
_ -> failure $ NotInScope occ
getCurrentDefinitions :: TacticsM [(OccName, CType)]
getCurrentDefinitions = do
ctx_funcs <- asks ctxDefiningFuncs
for ctx_funcs $ \res@(occ, _) ->
pure . maybe res (occ,) =<< lookupNameInContext occ
------------------------------------------------------------------------------
-- | Given two types, see if we can construct a homomorphism by mapping every
-- data constructor in the domain to the same in the codomain. This function
-- returns 'Just' when all the lookups succeeded, and a non-empty value if the
-- homomorphism *is not* possible.
uncoveredDataCons :: Type -> Type -> Maybe (S.Set (Uniquely DataCon))
uncoveredDataCons domain codomain = do
(g_dcs, _) <- tacticsGetDataCons codomain
(hi_dcs, _) <- tacticsGetDataCons domain
pure $ S.fromList (coerce hi_dcs) S.\\ S.fromList (coerce g_dcs)