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Implicit arguments in GF. Works only in PGF for now.

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krasimir
2009-10-02 13:25:12 +00:00
parent 40373704ff
commit 2732a7a22e
9 changed files with 168 additions and 44 deletions
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src/PGF/Expr.hs
+21 -3
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@@ -14,7 +14,7 @@ module PGF.Expr(Tree, BindType(..), Expr(..), Literal(..), Patt(..), Equation(..
MetaId,
-- helpers
pMeta,pStr,pFactor,pLit,freshName,ppMeta,ppLit,ppParens
pMeta,pStr,pArg,pLit,freshName,ppMeta,ppLit,ppParens
) where
import PGF.CId
@@ -56,7 +56,8 @@ data Expr =
| EMeta {-# UNPACK #-} !MetaId -- ^ meta variable
| EFun CId -- ^ function or data constructor
| EVar {-# UNPACK #-} !Int -- ^ variable with de Bruijn index
| ETyped Expr Type
| ETyped Expr Type -- ^ local type signature
| EImplArg Expr -- ^ implicit argument in expression
deriving (Eq,Ord,Show)
-- | The pattern is used to define equations in the abstract syntax of the grammar.
@@ -65,6 +66,7 @@ data Patt =
| PLit Literal -- ^ literal
| PVar CId -- ^ variable
| PWild -- ^ wildcard
| PImplArg Patt -- ^ implicit argument in pattern
deriving (Eq,Ord)
-- | The equation is used to define lambda function as a sequence
@@ -134,7 +136,10 @@ unDouble (ELit (LFlt f)) = Just f
pExpr :: RP.ReadP Expr
pExpr = RP.skipSpaces >> (pAbs RP.<++ pTerm)
where
pTerm = fmap (foldl1 EApp) (RP.sepBy1 pFactor RP.skipSpaces)
pTerm = do f <- pFactor
RP.skipSpaces
as <- RP.sepBy pArg RP.skipSpaces
return (foldl EApp f as)
pAbs = do xs <- RP.between (RP.char '\\') (RP.skipSpaces >> RP.string "->") pBinds
e <- pExpr
@@ -154,6 +159,10 @@ pBinds = do xss <- RP.sepBy1 (RP.skipSpaces >> pBind) (RP.skipSpaces >> RP.char
(RP.skipSpaces >> RP.char '}')
(RP.sepBy1 (RP.skipSpaces >> pCIdOrWild >>= \id -> return (Implicit,id)) (RP.skipSpaces >> RP.char ','))
pArg = fmap EImplArg (RP.between (RP.char '{') (RP.char '}') pExpr)
RP.<++
pFactor
pFactor = fmap EFun pCId
RP.<++ fmap ELit pLit
RP.<++ fmap EMeta pMeta
@@ -203,6 +212,7 @@ ppExpr d scope (EMeta n) = ppMeta n
ppExpr d scope (EFun f) = ppCId f
ppExpr d scope (EVar i) = ppCId (scope !! i)
ppExpr d scope (ETyped e ty)= PP.char '<' PP.<> ppExpr 0 scope e PP.<+> PP.colon PP.<+> ppType 0 scope ty PP.<> PP.char '>'
ppExpr d scope (EImplArg e) = PP.braces (ppExpr 0 scope e)
ppPatt :: Int -> [CId] -> Patt -> ([CId],PP.Doc)
ppPatt d scope (PApp f ps) = let (scope',ds) = mapAccumL (ppPatt 2) scope ps
@@ -210,6 +220,8 @@ ppPatt d scope (PApp f ps) = let (scope',ds) = mapAccumL (ppPatt 2) scope ps
ppPatt d scope (PLit l) = (scope,ppLit l)
ppPatt d scope (PVar f) = (f:scope,ppCId f)
ppPatt d scope PWild = (scope,PP.char '_')
ppPatt d scope (PImplArg p) = let (scope',d) = ppPatt 0 scope p
in (scope',PP.braces d)
ppBind Explicit x = ppCId x
ppBind Implicit x = PP.braces (ppCId x)
@@ -250,6 +262,7 @@ normalForm funs k env e = value2expr k (eval funs env e)
value2expr i (VSusp j env vs k) = value2expr i (k (VGen j vs))
value2expr i (VLit l) = ELit l
value2expr i (VClosure env (EAbs b x e)) = EAbs b x (value2expr (i+1) (eval funs ((VGen i []):env) e))
value2expr i (VImplArg v) = EImplArg (value2expr i v)
data Value
= VApp CId [Value]
@@ -258,6 +271,7 @@ data Value
| VSusp {-# UNPACK #-} !MetaId Env [Value] (Value -> Value)
| VGen {-# UNPACK #-} !Int [Value]
| VClosure Env Expr
| VImplArg Value
type Funs = Map.Map CId (Type,Int,[Equation]) -- type and def of a fun
type Env = [Value]
@@ -276,6 +290,7 @@ eval funs env (EAbs b x e) = VClosure env (EAbs b x e)
eval funs env (EMeta i) = VMeta i env []
eval funs env (ELit l) = VLit l
eval funs env (ETyped e _) = eval funs env e
eval funs env (EImplArg e) = VImplArg (eval funs env e)
apply :: Funs -> Env -> Expr -> [Value] -> Value
apply funs env e [] = eval funs env e
@@ -291,6 +306,7 @@ apply funs env (EAbs _ x e) (v:vs) = apply funs (v:env) e vs
apply funs env (EMeta i) vs = VMeta i env vs
apply funs env (ELit l) vs = error "literal of function type"
apply funs env (ETyped e _) vs = apply funs env e vs
apply funs env (EImplArg _) vs = error "implicit argument in function position"
applyValue funs v [] = v
applyValue funs (VApp f vs0) vs = apply funs [] (EFun f) (vs0++vs)
@@ -299,6 +315,7 @@ applyValue funs (VMeta i env vs0) vs = VMeta i env (vs0++vs)
applyValue funs (VGen i vs0) vs = VGen i (vs0++vs)
applyValue funs (VSusp i env vs0 k) vs = VSusp i env vs0 (\v -> applyValue funs (k v) vs)
applyValue funs (VClosure env (EAbs b x e)) (v:vs) = apply funs (v:env) e vs
applyValue funs (VImplArg _) vs = error "implicit argument in function position"
-----------------------------------------------------
-- Pattern matching
@@ -320,5 +337,6 @@ match funs f eqs as0 vs0 =
tryMatch (p ) (VSusp i envi vs k) env = VSusp i envi vs (\v -> tryMatch p (k v) env)
tryMatch (PApp f1 ps1) (VApp f2 vs2 ) env | f1 == f2 = tryMatches eqs (ps1++ps) (vs2++as) res env
tryMatch (PLit l1 ) (VLit l2 ) env | l1 == l2 = tryMatches eqs ps as res env
tryMatch (PImplArg p ) (VImplArg v ) env = tryMatch p v env
tryMatch _ _ env = match funs f eqs as0 vs0