Files
gf-core/src-3.0/GF/Conversion/SimpleToFCFG.hs
2008-05-23 09:54:02 +00:00

531 lines
25 KiB
Haskell

----------------------------------------------------------------------
-- |
-- Maintainer : Krasimir Angelov
-- Stability : (stable)
-- Portability : (portable)
--
-- Converting SimpleGFC grammars to fast nonerasing MCFG grammar.
--
-- the resulting grammars might be /very large/
--
-- the conversion is only equivalent if the GFC grammar has a context-free backbone.
-----------------------------------------------------------------------------
module GF.Conversion.SimpleToFCFG
(convertConcrete) where
import GF.Infra.PrintClass
import Control.Monad
import GF.Formalism.Utilities
import GF.Formalism.FCFG
import GF.GFCC.Macros --hiding (prt)
import GF.GFCC.DataGFCC
import GF.GFCC.CId
import GF.Data.BacktrackM
import GF.Data.SortedList
import GF.Data.Utilities (updateNthM, sortNub)
import qualified Data.Map as Map
import qualified Data.Set as Set
import qualified Data.List as List
import qualified Data.ByteString.Char8 as BS
import Data.Array
import Data.Maybe
----------------------------------------------------------------------
-- main conversion function
convertConcrete :: Abstr -> Concr -> FGrammar
convertConcrete abs cnc = fixHoasFuns $ convert abs_defs' conc' cats'
where abs_defs = Map.assocs (funs abs)
conc = Map.union (opers cnc) (lins cnc) -- "union big+small most efficient"
cats = lincats cnc
(abs_defs',conc',cats') = expandHOAS abs_defs conc cats
expandHOAS :: [(CId,(Type,Exp))] -> TermMap -> TermMap -> ([(CId,(Type,Exp))],TermMap,TermMap)
expandHOAS funs lins lincats = (funs' ++ hoFuns ++ varFuns,
Map.unions [lins, hoLins, varLins],
Map.unions [lincats, hoLincats, varLincat])
where
-- replace higher-order fun argument types with new categories
funs' = [(f,(fixType ty,e)) | (f,(ty,e)) <- funs]
where
fixType :: Type -> Type
fixType ty = let (ats,rt) = typeSkeleton ty in cftype (map catName ats) rt
hoTypes :: [(Int,CId)]
hoTypes = sortNub [(n,c) | (_,(ty,_)) <- funs, (n,c) <- fst (typeSkeleton ty), n > 0]
hoCats = sortNub (map snd hoTypes)
-- for each Cat with N bindings, we add a new category _NCat
-- each new category contains a single function __NCat : Cat -> _Var -> ... -> _Var -> _NCat
hoFuns = [(funName ty,(cftype (c : replicate n varCat) (catName ty),EEq [])) | ty@(n,c) <- hoTypes]
-- lincats for the new categories
hoLincats = Map.fromList [(catName ty, modifyRec (++ replicate n (S [])) (lincatOf c)) | ty@(n,c) <- hoTypes]
-- linearizations of the new functions, lin __NCat v_0 ... v_n-1 x = { s1 = x.s1; ...; sk = x.sk; $0 = v_0.s ...
hoLins = Map.fromList [ (funName ty, mkLin c n) | ty@(n,c) <- hoTypes]
where mkLin c n = modifyRec (\fs -> [P (V 0) (C j) | j <- [0..length fs-1]] ++ [P (V i) (C 0) | i <- [1..n]]) (lincatOf c)
-- for each Cat, we a add a fun _Var_Cat : _Var -> Cat
varFuns = [(varFunName cat, (cftype [varCat] cat,EEq [])) | cat <- hoCats]
-- linearizations of the _Var_Cat functions
varLins = Map.fromList [(varFunName cat, R [P (V 0) (C 0)]) | cat <- hoCats]
-- lincat for the _Var category
varLincat = Map.singleton varCat (R [S []])
lincatOf c = fromMaybe (error $ "No lincat for " ++ prt c) $ Map.lookup c lincats
modifyRec :: ([Term] -> [Term]) -> Term -> Term
modifyRec f (R xs) = R (f xs)
modifyRec _ t = error $ "Not a record: " ++ show t
varCat = mkCId "_Var"
catName :: (Int,CId) -> CId
catName (0,c) = c
catName (n,c) = mkCId ("_" ++ show n ++ prt c)
funName :: (Int,CId) -> CId
funName (n,c) = mkCId ("__" ++ show n ++ prt c)
varFunName :: CId -> CId
varFunName c = mkCId ("_Var_" ++ prt c)
-- replaces __NCat with _B and _Var_Cat with _.
-- the temporary names are just there to avoid name collisions.
fixHoasFuns :: FGrammar -> FGrammar
fixHoasFuns (rs, cs) = ([FRule (fixName n) args cat lins | FRule n args cat lins <- rs], cs)
where fixName (Name (CId n) p) | BS.pack "__" `BS.isPrefixOf` n = Name (mkCId "_B") p
| BS.pack "_Var_" `BS.isPrefixOf` n = Name wildCId p
fixName n = n
convert :: [(CId,(Type,Exp))] -> TermMap -> TermMap -> FGrammar
convert abs_defs cnc_defs cat_defs = getFGrammar (loop frulesEnv)
where
srules = [
(XRule id args res (map findLinType args) (findLinType res) term) |
(id, (ty,_)) <- abs_defs, let (args,res) = catSkeleton ty,
term <- Map.lookup id cnc_defs]
findLinType id = fromMaybe (error $ "No lincat for " ++ show id) (Map.lookup id cat_defs)
(xrulesMap,frulesEnv) = List.foldl' helper (Map.empty,emptyFRulesEnv) srules
where
helper (xrulesMap,frulesEnv) rule@(XRule id abs_args abs_res cnc_args cnc_res term) =
let xrulesMap' = Map.insertWith (++) abs_res [rule] xrulesMap
frulesEnv' = List.foldl' (\env selector -> convertRule cnc_defs selector rule env)
frulesEnv
(mkSingletonSelectors cnc_defs cnc_res)
in xrulesMap' `seq` frulesEnv' `seq` (xrulesMap',frulesEnv')
loop frulesEnv =
let (todo, frulesEnv') = takeToDoRules xrulesMap frulesEnv
in case todo of
[] -> frulesEnv'
_ -> loop $! List.foldl' (\env (srules,selector) ->
List.foldl' (\env srule -> convertRule cnc_defs selector srule env) env srules) frulesEnv' todo
convertRule :: TermMap -> TermSelector -> XRule -> FRulesEnv -> FRulesEnv
convertRule cnc_defs selector (XRule fun args cat ctypes ctype term) frulesEnv =
foldBM addRule
frulesEnv
(convertTerm cnc_defs selector term [([],[])])
(protoFCat cat, map (\scat -> (protoFCat scat,[])) args, ctype, ctypes)
where
addRule linRec (newCat', newArgs', _, _) env0 =
let (env1, newCat) = genFCatHead env0 newCat'
(env2, newArgs,idxArgs) = foldr (\((xcat@(PFCat cat rcs tcs),xpaths),ctype,idx) (env,args,all_args) ->
let xargs = xcat:[PFCat cat [path] tcs | path <- reverse xpaths]
(env1, xargs1) = List.mapAccumL (genFCatArg cnc_defs ctype) env xargs
in case xcat of
PFCat _ [] _ -> (env , args, all_args)
_ -> (env1,xargs1++args,(idx,zip xargs1 xargs):all_args)) (env1,[],[]) (zip3 newArgs' ctypes [0..])
newLinRec = listArray (0,length linRec-1) [translateLin idxArgs path linRec | path <- case newCat' of {PFCat _ rcs _ -> rcs}]
(_,newProfile) = List.mapAccumL accumProf 0 newArgs'
where
accumProf nr (PFCat _ [] _,_ ) = (nr, Unify [] )
accumProf nr (_ ,xpaths) = (nr+cnt+1, Unify [nr..nr+cnt])
where cnt = length xpaths
rule = FRule (Name fun newProfile) newArgs newCat newLinRec
in addFRule env2 rule
translateLin idxArgs lbl' [] = array (0,-1) []
translateLin idxArgs lbl' ((lbl,syms) : lins)
| lbl' == lbl = listArray (0,length syms-1) (map instSym syms)
| otherwise = translateLin idxArgs lbl' lins
where
instSym = symbol (\(lbl, nr, xnr) -> instCat lbl nr xnr 0 idxArgs) FSymTok
instCat lbl nr xnr nr' ((idx,xargs):idxArgs)
| nr == idx = let (fcat, PFCat _ rcs _) = xargs !! xnr
in FSymCat fcat (index lbl rcs 0) (nr'+xnr)
| otherwise = instCat lbl nr xnr (nr'+length xargs) idxArgs
index lbl' (lbl:lbls) idx
| lbl' == lbl = idx
| otherwise = index lbl' lbls $! (idx+1)
----------------------------------------------------------------------
-- term conversion
type CnvMonad a = BacktrackM Env a
type Env = (ProtoFCat, [(ProtoFCat,[FPath])], Term, [Term])
type LinRec = [(FPath, [Symbol (FPath, FIndex, Int) FToken])]
type TermMap = Map.Map CId Term
convertTerm :: TermMap -> TermSelector -> Term -> LinRec -> CnvMonad LinRec
convertTerm cnc_defs selector (V nr) ((lbl_path,lin) : lins) = convertArg selector nr [] lbl_path lin lins
convertTerm cnc_defs selector (C nr) ((lbl_path,lin) : lins) = convertCon selector nr lbl_path lin lins
convertTerm cnc_defs selector (R record) ((lbl_path,lin) : lins) = convertRec cnc_defs selector 0 record lbl_path lin lins
convertTerm cnc_defs selector (P term sel) lins = do nr <- evalTerm cnc_defs [] sel
convertTerm cnc_defs (TuplePrj nr selector) term lins
convertTerm cnc_defs selector (FV vars) lins = do term <- member vars
convertTerm cnc_defs selector term lins
convertTerm cnc_defs selector (S ts) ((lbl_path,lin) : lins) = do projectHead lbl_path
foldM (\lins t -> convertTerm cnc_defs selector t lins) ((lbl_path,lin) : lins) (reverse ts)
convertTerm cnc_defs selector (K (KS str)) ((lbl_path,lin) : lins) =
do projectHead lbl_path
return ((lbl_path,Tok str : lin) : lins)
convertTerm cnc_defs selector (K (KP strs vars))((lbl_path,lin) : lins) =
do projectHead lbl_path
toks <- member (strs:[strs' | Var strs' _ <- vars])
return ((lbl_path, map Tok toks ++ lin) : lins)
convertTerm cnc_defs selector (F id) lins = do term <- Map.lookup id cnc_defs
convertTerm cnc_defs selector term lins
convertTerm cnc_defs selector (W s t) ((lbl_path,lin) : lins) = do
ss <- case t of
R ss -> return ss
F f -> do
t <- Map.lookup f cnc_defs
case t of
R ss -> return ss
convertRec cnc_defs selector 0 [K (KS (s ++ s1)) | K (KS s1) <- ss] lbl_path lin lins
convertTerm cnc_defs selector x lins = error ("convertTerm ("++show x++")")
convertArg (TupleSel record) nr path lbl_path lin lins =
foldM (\lins (lbl, selector) -> convertArg selector nr (lbl:path) (lbl:lbl_path) lin lins) lins record
convertArg (TuplePrj lbl selector) nr path lbl_path lin lins =
convertArg selector nr (lbl:path) lbl_path lin lins
convertArg (ConSel indices) nr path lbl_path lin lins = do
index <- member indices
restrictHead lbl_path index
restrictArg nr path index
return lins
convertArg StrSel nr path lbl_path lin lins = do
projectHead lbl_path
xnr <- projectArg nr path
return ((lbl_path, GF.Formalism.Utilities.Cat (path, nr, xnr) : lin) : lins)
convertCon (ConSel indices) index lbl_path lin lins = do
guard (index `elem` indices)
restrictHead lbl_path index
return lins
convertCon x _ _ _ _ = error $ "SimpleToFCFG,convertCon: " ++ show x
convertRec cnc_defs selector index [] lbl_path lin lins = return lins
convertRec cnc_defs selector@(TupleSel fields) index (val:record) lbl_path lin lins = select fields
where
select [] = convertRec cnc_defs selector (index+1) record lbl_path lin lins
select ((index',sub_sel) : fields)
| index == index' = do lins <- convertTerm cnc_defs sub_sel val ((index:lbl_path,lin) : lins)
convertRec cnc_defs selector (index+1) record lbl_path lin lins
| otherwise = select fields
convertRec cnc_defs (TuplePrj index' sub_sel) index record lbl_path lin lins = do
convertTerm cnc_defs sub_sel (record !! (index'-index)) ((lbl_path,lin) : lins)
------------------------------------------------------------
-- eval a term to ground terms
evalTerm :: TermMap -> FPath -> Term -> CnvMonad FIndex
evalTerm cnc_defs path (V nr) = do term <- readArgCType nr
unifyPType nr (reverse path) (selectTerm path term)
evalTerm cnc_defs path (C nr) = return nr
evalTerm cnc_defs path (R record) = case path of
(index:path) -> evalTerm cnc_defs path (record !! index)
evalTerm cnc_defs path (P term sel) = do index <- evalTerm cnc_defs [] sel
evalTerm cnc_defs (index:path) term
evalTerm cnc_defs path (FV terms) = member terms >>= evalTerm cnc_defs path
evalTerm cnc_defs path (F id) = do term <- Map.lookup id cnc_defs
evalTerm cnc_defs path term
evalTerm cnc_defs path x = error ("evalTerm ("++show x++")")
unifyPType :: FIndex -> FPath -> Term -> CnvMonad FIndex
unifyPType nr path (C max_index) =
do (_, args, _, _) <- readState
let (PFCat _ _ tcs,_) = args !! nr
case lookup path tcs of
Just index -> return index
Nothing -> do index <- member [0..max_index]
restrictArg nr path index
return index
unifyPType nr path t = error $ "unifyPType " ++ show t ---- AR 2/10/2007
selectTerm :: FPath -> Term -> Term
selectTerm [] term = term
selectTerm (index:path) (R record) = selectTerm path (record !! index)
----------------------------------------------------------------------
-- FRulesEnv
data FRulesEnv = FRulesEnv {-# UNPACK #-} !Int FCatSet [FRule]
type FCatSet = Map.Map CId (Map.Map [FPath] (Map.Map [(FPath,FIndex)] (Either FCat FCat)))
data ProtoFCat = PFCat CId [FPath] [(FPath,FIndex)]
protoFCat :: CId -> ProtoFCat
protoFCat cat = PFCat cat [] []
emptyFRulesEnv = FRulesEnv 0 (ins fcatString (mkCId "String") [[0]] [] $
ins fcatInt (mkCId "Int") [[0]] [] $
ins fcatFloat (mkCId "Float") [[0]] [] $
ins fcatVar (mkCId "_Var") [[0]] [] $
Map.empty) []
where
ins fcat cat rcs tcs fcatSet =
Map.insertWith (\_ -> Map.insertWith (\_ -> Map.insert tcs right_fcat) rcs tmap_s) cat rmap_s fcatSet
where
right_fcat = Right fcat
tmap_s = Map.singleton tcs right_fcat
rmap_s = Map.singleton rcs tmap_s
addFRule :: FRulesEnv -> FRule -> FRulesEnv
addFRule (FRulesEnv last_id fcatSet rules) rule = FRulesEnv last_id fcatSet (rule:rules)
getFGrammar :: FRulesEnv -> FGrammar
getFGrammar (FRulesEnv last_id fcatSet rules) = (rules, Map.map getFCatList fcatSet)
where
getFCatList rcs = Map.fold (\tcs lst -> Map.fold (\x lst -> either id id x : lst) lst tcs) [] rcs
genFCatHead :: FRulesEnv -> ProtoFCat -> (FRulesEnv, FCat)
genFCatHead env@(FRulesEnv last_id fcatSet rules) (PFCat cat rcs tcs) =
case Map.lookup cat fcatSet >>= Map.lookup rcs >>= Map.lookup tcs of
Just (Left fcat) -> (FRulesEnv last_id (ins fcat) rules, fcat)
Just (Right fcat) -> (env, fcat)
Nothing -> let fcat = last_id+1
in (FRulesEnv fcat (ins fcat) rules, fcat)
where
ins fcat = Map.insertWith (\_ -> Map.insertWith (\_ -> Map.insert tcs right_fcat) rcs tmap_s) cat rmap_s fcatSet
where
right_fcat = Right fcat
tmap_s = Map.singleton tcs right_fcat
rmap_s = Map.singleton rcs tmap_s
genFCatArg :: TermMap -> Term -> FRulesEnv -> ProtoFCat -> (FRulesEnv, FCat)
genFCatArg cnc_defs ctype env@(FRulesEnv last_id fcatSet rules) (PFCat cat rcs tcs) =
case Map.lookup cat fcatSet >>= Map.lookup rcs of
Just tmap -> case Map.lookup tcs tmap of
Just (Left fcat) -> (env, fcat)
Just (Right fcat) -> (env, fcat)
Nothing -> ins tmap
Nothing -> ins Map.empty
where
ins tmap =
let fcat = last_id+1
(either_fcat,last_id1,tmap1,rules1)
= foldBM (\tcs st (either_fcat,last_id,tmap,rules) ->
let (last_id1,tmap1,fcat_arg) = addArg tcs last_id tmap
rule = FRule (Name wildCId [Unify [0]]) [fcat_arg] fcat
(listArray (0,length rcs-1) [listArray (0,0) [FSymCat fcat_arg lbl 0] | lbl <- [0..length rcs-1]])
in if st
then (Right fcat, last_id1,tmap1,rule:rules)
else (either_fcat,last_id, tmap, rules))
(Left fcat,fcat,Map.insert tcs either_fcat tmap,rules)
(gen_tcs ctype [] [])
False
rmap1 = Map.singleton rcs tmap1
in (FRulesEnv last_id1 (Map.insertWith (\_ -> Map.insert rcs tmap1) cat rmap1 fcatSet) rules1, fcat)
where
addArg tcs last_id tmap =
case Map.lookup tcs tmap of
Just (Left fcat) -> (last_id, tmap, fcat)
Just (Right fcat) -> (last_id, tmap, fcat)
Nothing -> let fcat = last_id+1
in (fcat, Map.insert tcs (Left fcat) tmap, fcat)
gen_tcs :: Term -> FPath -> [(FPath,FIndex)] -> BacktrackM Bool [(FPath,FIndex)]
gen_tcs (R record) path acc = foldM (\acc (label,ctype) -> gen_tcs ctype (label:path) acc) acc (zip [0..] record)
gen_tcs (S _) path acc = return acc
gen_tcs (C max_index) path acc =
case List.lookup path tcs of
Just index -> return $! addConstraint path index acc
Nothing -> do writeState True
index <- member [0..max_index]
return $! addConstraint path index acc
where
addConstraint path0 index0 (c@(path,index) : cs)
| path0 > path = c:addConstraint path0 index0 cs
addConstraint path0 index0 cs = (path0,index0) : cs
gen_tcs (F id) path acc = case Map.lookup id cnc_defs of
Just term -> gen_tcs term path acc
Nothing -> error ("unknown identifier: "++prt id)
------------------------------------------------------------
-- TODO queue organization
type XRulesMap = Map.Map CId [XRule]
data XRule = XRule CId {- function -}
[CId] {- argument types -}
CId {- result type -}
[Term] {- argument lin-types representation -}
Term {- result lin-type representation -}
Term {- body -}
takeToDoRules :: XRulesMap -> FRulesEnv -> ([([XRule], TermSelector)], FRulesEnv)
takeToDoRules xrulesMap (FRulesEnv last_id fcatSet rules) = (todo,FRulesEnv last_id fcatSet' rules)
where
(todo,fcatSet') =
Map.mapAccumWithKey (\todo cat rmap ->
let (todo1,rmap1) = Map.mapAccumWithKey (\todo rcs tmap ->
let (tcss,tmap') = Map.mapAccumWithKey (\tcss tcs either_xcat ->
case either_xcat of
Left xcat -> (tcs:tcss,Right xcat)
Right xcat -> ( tcss,either_xcat)) [] tmap
in case tcss of
[] -> ( todo,tmap )
_ -> ((srules,mkSelector rcs tcss) : todo,tmap')) todo rmap
mb_srules = Map.lookup cat xrulesMap
Just srules = mb_srules
in case mb_srules of
Just srules -> (todo1,rmap1)
Nothing -> (todo ,rmap1)) [] fcatSet
------------------------------------------------------------
-- The TermSelector
data TermSelector
= TupleSel [(FIndex, TermSelector)]
| TuplePrj FIndex TermSelector
| ConSel [FIndex]
| StrSel
deriving Show
mkSingletonSelectors :: TermMap
-> Term -- ^ Type representation term
-> [TermSelector] -- ^ list of selectors containing just one string field
mkSingletonSelectors cnc_defs term = sels0
where
(sels0,tcss0) = loop [] ([],[]) term
loop path st (R record) = List.foldl' (\st (index,term) -> loop (index:path) st term) st (zip [0..] record)
loop path (sels,tcss) (C i) = ( sels,map ((,) path) [0..i] : tcss)
loop path (sels,tcss) (S _) = (mkSelector [path] tcss0 : sels, tcss)
loop path (sels,tcss) (F id) = case Map.lookup id cnc_defs of
Just term -> loop path (sels,tcss) term
Nothing -> error ("unknown identifier: "++prt id)
mkSelector :: [FPath] -> [[(FPath,FIndex)]] -> TermSelector
mkSelector rcs tcss =
List.foldl' addRestriction (case xs of
(path:xs) -> List.foldl' addProjection (path2selector StrSel path) xs) ys
where
xs = [ reverse path | path <- rcs]
ys = [(reverse path,term) | tcs <- tcss, (path,term) <- tcs]
addRestriction :: TermSelector -> (FPath,FIndex) -> TermSelector
addRestriction (ConSel indices) ([] ,n_index) = ConSel (add indices)
where
add [] = [n_index]
add (index':indices)
| n_index == index' = index': indices
| otherwise = index':add indices
addRestriction (TupleSel fields) (index : path,n_index) = TupleSel (add fields)
where
add [] = [(index,path2selector (ConSel [n_index]) path)]
add (field@(index',sub_sel):fields)
| index == index' = (index',addRestriction sub_sel (path,n_index)):fields
| otherwise = field : add fields
addProjection :: TermSelector -> FPath -> TermSelector
addProjection StrSel [] = StrSel
addProjection (TupleSel fields) (index : path) = TupleSel (add fields)
where
add [] = [(index,path2selector StrSel path)]
add (field@(index',sub_sel):fields)
| index == index' = (index',addProjection sub_sel path):fields
| otherwise = field : add fields
path2selector base [] = base
path2selector base (index : path) = TupleSel [(index,path2selector base path)]
------------------------------------------------------------
-- updating the MCF rule
readArgCType :: FIndex -> CnvMonad Term
readArgCType nr = do (_, _, _, ctypes) <- readState
return (ctypes !! nr)
restrictArg :: FIndex -> FPath -> FIndex -> CnvMonad ()
restrictArg nr path index = do
(head, args, ctype, ctypes) <- readState
args' <- updateNthM (\(xcat,xs) -> do xcat <- restrictProtoFCat path index xcat
return (xcat,xs) ) nr args
writeState (head, args', ctype, ctypes)
projectArg :: FIndex -> FPath -> CnvMonad Int
projectArg nr path = do
(head, args, ctype, ctypes) <- readState
(xnr,args') <- updateArgs nr args
writeState (head, args', ctype, ctypes)
return xnr
where
updateArgs :: FIndex -> [(ProtoFCat,[FPath])] -> CnvMonad (Int,[(ProtoFCat,[FPath])])
updateArgs 0 ((a@(PFCat _ rcs _),xpaths) : as)
| path `elem` rcs = return (length xpaths+1,(a,path:xpaths):as)
| otherwise = do a <- projectProtoFCat path a
return (0,(a,xpaths):as)
updateArgs n (a : as) = do
(xnr,as) <- updateArgs (n-1) as
return (xnr,a:as)
readHeadCType :: CnvMonad Term
readHeadCType = do (_, _, ctype, _) <- readState
return ctype
restrictHead :: FPath -> FIndex -> CnvMonad ()
restrictHead path term
= do (head, args, ctype, ctypes) <- readState
head' <- restrictProtoFCat path term head
writeState (head', args, ctype, ctypes)
projectHead :: FPath -> CnvMonad ()
projectHead path
= do (head, args, ctype, ctypes) <- readState
head' <- projectProtoFCat path head
writeState (head', args, ctype, ctypes)
restrictProtoFCat :: FPath -> FIndex -> ProtoFCat -> CnvMonad ProtoFCat
restrictProtoFCat path0 index0 (PFCat cat rcs tcs) = do
tcs <- addConstraint tcs
return (PFCat cat rcs tcs)
where
addConstraint (c@(path,index) : cs)
| path0 > path = liftM (c:) (addConstraint cs)
| path0 == path = guard (index0 == index) >>
return (c : cs)
addConstraint cs = return ((path0,index0) : cs)
projectProtoFCat :: FPath -> ProtoFCat -> CnvMonad ProtoFCat
projectProtoFCat path0 (PFCat cat rcs tcs) = do
return (PFCat cat (addConstraint rcs) tcs)
where
addConstraint (path : rcs)
| path0 > path = path : addConstraint rcs
| path0 == path = path : rcs
addConstraint rcs = path0 : rcs