ddc-core-simpl-0.4.3.1: DDC/Core/Transform/Eta.hs
-- Eta-expand functional values.
---
-- NOTE: This is module currently just does eta-expansion, but in future
-- we should expand the config to also make it do expansion/contraction
-- based on the real arity of bindings.
--
module DDC.Core.Transform.Eta
( Config(..)
, configZero
, Info (..)
, etaModule
, etaX)
where
import qualified DDC.Core.Check as Check
import DDC.Core.Module
import DDC.Core.Exp.Annot
import DDC.Core.Fragment
import DDC.Core.Transform.BoundX
import DDC.Core.Transform.BoundT
import DDC.Core.Simplifier.Result
import DDC.Core.Pretty
import DDC.Type.Transform.AnonymizeT
import Control.Monad.Writer (Writer, tell, runWriter)
import Data.Typeable
import DDC.Core.Env.EnvX (EnvX)
import qualified DDC.Core.Env.EnvX as EnvX
import Prelude hiding ((<$>))
-------------------------------------------------------------------------------
data Config
= Config
{ configExpand :: Bool }
deriving Show
-- | Empty eta configuration with all flags set to False.
configZero :: Config
configZero
= Config
{ configExpand = False }
-------------------------------------------------------------------------------
data Info
= Info
{ -- | Number of level-1 lambdas added.
infoExpandedXLAMs :: Int
-- | Number of level-0 lambdas added.
, infoExpandedXLams :: Int }
deriving Typeable
instance Pretty Info where
ppr (Info ex1 ex0)
= text "Eta Transform"
<$> indent 4 (vcat
[ text "level-1 lambdas added: " <> int ex1
, text "level-0 lambdas added: " <> int ex0 ])
instance Monoid Info where
mempty = Info 0 0
mappend (Info ex1 ex0)
(Info ex1' ex0')
= Info (ex1 + ex1') (ex0 + ex0')
-- Module ---------------------------------------------------------------------
-- | Eta-transform expressions in a module.
etaModule
:: (Ord n, Show n, Pretty n, Show a)
=> Profile n
-> Config
-> Module a n
-> TransformResult (Module a n)
etaModule profile config mm
= let
-- Slurp type checker config.
cconfig = Check.configOfProfile profile
-- Slurp the top level environment.
env = moduleEnvX
(profilePrimKinds profile)
(profilePrimTypes profile)
(profilePrimDataDefs profile)
mm
-- Run the eta transform.
(mm', info) = runWriter $ etaM config cconfig env mm
-- Check if any actual work was performed
progress
= case info of
Info ex1 ex0
-> ex1 + ex0 > 0
in TransformResult
{ result = mm'
, resultAgain = False
, resultProgress = progress
, resultInfo = TransformInfo info }
-- | Eta-transform an expression.
etaX :: (Ord n, Show n, Show a, Pretty n)
=> Profile n -- ^ Language profile.
-> Config -- ^ Eta-transform config.
-> EnvX n -- ^ Type checker environment.
-> Exp a n -- ^ Expression to transform.
-> TransformResult (Exp a n)
etaX profile config env xx
= let cconfig = Check.configOfProfile profile
-- Run the eta transform.
(xx', info)
= runWriter
$ etaM config cconfig env xx
-- Check if any actual work was performed
progress
= case info of
Info ex1 ex0
-> ex1 + ex0 > 0
in TransformResult
{ result = xx'
, resultAgain = False
, resultProgress = progress
, resultInfo = TransformInfo info }
-------------------------------------------------------------------------------
class Eta (c :: * -> * -> *) where
etaM :: (Show a, Ord n, Pretty n, Show n)
=> Config -- ^ Eta-transform config.
-> Check.Config n -- ^ Type checker config.
-> EnvX n -- ^ Type checker environment.
-> c a n -- ^ Do eta-expansion in this thing.
-> Writer Info (c a n)
instance Eta Module where
etaM config cconfig envx mm
= do -- The top level environment of the module is added
-- by the etaModule wrapper, so we don't need to do it again.
xx' <- etaM config cconfig envx (moduleBody mm)
return $ mm { moduleBody = xx' }
instance Eta Exp where
etaM config cconfig env xx
= let down = etaM config cconfig env
in case xx of
XVar a _
| configExpand config
, Right tX <- Check.typeOfExp cconfig env xx
-> do etaExpand a tX xx
XApp a _ _
| configExpand config
, Right tX <- Check.typeOfExp cconfig env xx
-> do
-- Decend into the arguments first.
-- We don't need to decend into the function part because
-- we're eta-expanding that here.
let (x : xs) = takeXAppsAsList xx
xs_eta <- mapM down xs
-- Now eta expand the result.
etaExpand a tX $ xApps a x xs_eta
XLAM a b x
-> do let env' = EnvX.extendT b env
x' <- etaM config cconfig env' x
return $ XLAM a b x'
XLam a b x
-> do let env' = EnvX.extendX b env
x' <- etaM config cconfig env' x
return $ XLam a b x'
XLet a lts x2
-> do lts' <- down lts
let (bs1, bs0) = bindsOfLets lts
let env' = EnvX.extendsT bs1
$ EnvX.extendsX bs0 env
x2' <- etaM config cconfig env' x2
return $ XLet a lts' x2'
XCase a x alts
-> do x' <- down x
alts' <- mapM (etaM config cconfig env) alts
return $ XCase a x' alts'
XCast a cc x
-> do x' <- down x
return $ XCast a cc x'
_ -> return xx
instance Eta Lets where
etaM config cconfig env lts
= let down = etaM config cconfig env
in case lts of
LLet b x
-> do x' <- down x
return $ LLet b x'
LRec bxs
-> do let bs = map fst bxs
let env' = EnvX.extendsX bs env
xs' <- mapM (etaM config cconfig env')
$ map snd bxs
return $ LRec (zip bs xs')
LPrivate{}
-> return lts
instance Eta Alt where
etaM config cconfig env alt
= case alt of
AAlt p x
-> do let bs = bindsOfPat p
let env' = EnvX.extendsX bs env
x' <- etaM config cconfig env' x
return $ AAlt p x'
-- Expand ---------------------------------------------------------------------
-- | Eta expand an expression.
etaExpand
:: Ord n
=> a -- ^ Annotation to use for new AST nodes.
-> Type n -- ^ Type of the expression.
-> Exp a n -- ^ Inner expression to wrap.
-> Writer Info (Exp a n)
etaExpand a tX xx
-- Anonymize the type, so any references to foralls will become anonymous.
-- Then, when we add the anonymous bindings, it will work out.
= do let btsMore = expandableArgs $ anonymizeT tX
xx' <- etaExpand' a 0 0 [] btsMore xx
return xx'
-- | Decide what type arguments need to be eta-expanded.
expandableArgs :: Type n -> [(Bool, Type n)]
expandableArgs tt
| TForall b t' <- tt
= (True, typeOfBind b) : expandableArgs t'
| Just (t1, t2) <- takeTFun tt
= (False, t1) : expandableArgs t2
| otherwise
= []
-- | Eta-expand an expression.
etaExpand'
:: Ord n
=> a -- ^ Annotation to use for the new AST nodes.
-> Int -- ^ Number of level-1 lambdas we've added so far.
-> Int -- ^ Number of level-0 lambdas we've added so far.
-> [Exp a n] -- ^ Accumulate arguments we need to add to the
-- inner expression.
-> [(Bool, Type n)] -- ^ Types of bindings we need to add, along with
-- a flag to indicate level-1 or level-0 binder
-> Exp a n -- ^ Inner expression that is being applied.
-> Writer Info (Exp a n)
etaExpand' a levels1 levels0 args [] xx
= do let xx' = liftT levels1 $ liftX levels0 xx
return $ xApps a xx' args
etaExpand' a levels1 levels0 args ((True, t) : ts) xx
= do let depth1 = length $ filter ((== True) . fst) ts
xx' <- etaExpand' a (levels1 + 1) levels0
(args ++ [XType a (TVar (UIx depth1))])
ts
xx
tell mempty { infoExpandedXLAMs = 1 }
return $ XLAM a (BAnon t) xx'
etaExpand' a levels1 levels0 args ((False, t) : ts) xx
= do let depth0 = length $ filter ((== False) . fst) ts
xx' <- etaExpand' a
levels1 (levels0 + 1)
(args ++ [XVar a (UIx depth0)])
ts
xx
tell mempty { infoExpandedXLams = 1 }
return $ XLam a (BAnon t) xx'