ddc-core-simpl-0.3.2.1: 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
import DDC.Core.Fragment
import DDC.Core.Transform.LiftX
import DDC.Core.Transform.LiftT
import DDC.Core.Simplifier.Result
import DDC.Core.Compounds
import DDC.Core.Pretty
import DDC.Type.Env (TypeEnv, KindEnv)
import Control.Monad.Writer (Writer, tell, runWriter)
import Data.Monoid (Monoid, mempty, mappend)
import qualified DDC.Type.Env as Env
import Data.Typeable
-------------------------------------------------------------------------------
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)
=> Config
-> Profile n
-> Module a n
-> TransformResult (Module a n)
etaModule config profile mm
= let cconfig = Check.configOfProfile profile
kenv' = Env.union (profilePrimKinds profile) (moduleKindEnv mm)
tenv' = Env.union (profilePrimTypes profile) (moduleTypeEnv mm)
-- Run the eta transform.
(mm', info)
= runWriter
$ etaM config cconfig kenv' tenv' 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)
=> Config -- ^ Eta-transform config.
-> Profile n -- ^ Language profile.
-> KindEnv n -- ^ Kind environment.
-> TypeEnv n -- ^ Type environment.
-> Exp a n -- ^ Expression to transform.
-> TransformResult (Exp a n)
etaX config profile kenv tenv xx
= let cconfig = Check.configOfProfile profile
kenv' = Env.union (profilePrimKinds profile) kenv
tenv' = Env.union (profilePrimTypes profile) tenv
-- Run the eta transform.
(xx', info)
= runWriter
$ etaM config cconfig kenv' tenv' 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 :: (Ord n, Pretty n, Show n)
=> Config -- ^ Eta-transform config.
-> Check.Config n -- ^ Type checker config.
-> KindEnv n -- ^ Kind environment.
-> TypeEnv n -- ^ Type environment.
-> c a n -- ^ Do eta-expansion in this thing.
-> Writer Info (c a n)
instance Eta Module where
etaM config cconfig kenv tenv mm
= do let kenv' = Env.union (moduleKindEnv mm) kenv
let tenv' = Env.union (moduleTypeEnv mm) tenv
xx' <- etaM config cconfig kenv' tenv' (moduleBody mm)
return $ mm { moduleBody = xx' }
instance Eta Exp where
etaM config cconfig kenv tenv xx
= let down = etaM config cconfig kenv tenv
in case xx of
XVar a _
| configExpand config
, Right tX <- Check.typeOfExp cconfig kenv tenv xx
-> do etaExpand a tX xx
XApp a _ _
| configExpand config
, Right tX <- Check.typeOfExp cconfig kenv tenv 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 kenv' = Env.extend b kenv
x' <- etaM config cconfig kenv' tenv x
return $ XLAM a b x'
XLam a b x
-> do let tenv' = Env.extend b tenv
x' <- etaM config cconfig kenv tenv' x
return $ XLam a b x'
XLet a lts x2
-> do lts' <- down lts
let (bs1, bs0) = bindsOfLets lts
let kenv' = Env.extends bs1 kenv
let tenv' = Env.extends bs0 tenv
x2' <- etaM config cconfig kenv' tenv' x2
return $ XLet a lts' x2'
XCase a x alts
-> do x' <- down x
alts' <- mapM (etaM config cconfig kenv tenv) 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 kenv tenv lts
= let down = etaM config cconfig kenv tenv
in case lts of
LLet b x
-> do x' <- down x
return $ LLet b x'
LRec bxs
-> do let bs = map fst bxs
let tenv' = Env.extends bs tenv
xs' <- mapM (etaM config cconfig kenv tenv')
$ map snd bxs
return $ LRec (zip bs xs')
LLetRegions{} -> return lts
LWithRegion{} -> return lts
instance Eta Alt where
etaM config cconfig kenv tenv alt
= case alt of
AAlt p x
-> do let bs = bindsOfPat p
let tenv' = Env.extends bs tenv
x' <- etaM config cconfig kenv tenv' 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
= do let btsMore = expandableArgs 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 (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'