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now in the command shell the primary type in the pipe is Expr not Tree. This makes the pt -compute and pt -typecheck more interesting

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krasimir
2009-05-23 21:33:52 +00:00
parent f9c877eec6
commit 0c46a129e6
10 changed files with 110 additions and 95 deletions
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95
src/PGF/Expr.hs
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@@ -4,7 +4,7 @@ module PGF.Expr(Tree(..), Literal(..),
Expr(..), Patt(..), Equation(..),
readExpr, showExpr, pExpr, ppExpr, ppPatt,
tree2expr, expr2tree,
tree2expr, expr2tree, normalForm,
-- needed in the typechecker
Value(..), Env, eval, apply, eqValue,
@@ -42,9 +42,7 @@ data Tree =
deriving (Eq, Ord)
-- | An expression represents a potentially unevaluated expression
-- in the abstract syntax of the grammar. It can be evaluated with
-- the 'expr2tree' function and then linearized or it can be used
-- directly in the dependent types.
-- in the abstract syntax of the grammar.
data Expr =
EAbs CId Expr -- ^ lambda abstraction
| EApp Expr Expr -- ^ application
@@ -111,7 +109,7 @@ pTrees :: RP.ReadP [Tree]
pTrees = liftM2 (:) (pTree True) pTrees RP.<++ (RP.skipSpaces >> return [])
pTree :: Bool -> RP.ReadP Tree
pTree isNested = RP.skipSpaces >> (pParen RP.<++ pAbs RP.<++ pApp RP.<++ fmap Lit pLit RP.<++ pMeta)
pTree isNested = RP.skipSpaces >> (pParen RP.<++ pAbs RP.<++ pApp RP.<++ fmap Lit pLit RP.<++ fmap Meta pMeta)
where
pParen = RP.between (RP.char '(') (RP.char ')') (pTree False)
pAbs = do xs <- RP.between (RP.char '\\') (RP.skipSpaces >> RP.string "->") (RP.sepBy1 (RP.skipSpaces >> pCId) (RP.skipSpaces >> RP.char ','))
@@ -120,9 +118,6 @@ pTree isNested = RP.skipSpaces >> (pParen RP.<++ pAbs RP.<++ pApp RP.<++ fmap Li
pApp = do f <- pCId
ts <- (if isNested then return [] else pTrees)
return (Fun f ts)
pMeta = do RP.char '?'
n <- fmap read (RP.munch1 isDigit)
return (Meta n)
pExpr :: RP.ReadP Expr
pExpr = RP.skipSpaces >> (pAbs RP.<++ pTerm)
@@ -133,14 +128,16 @@ pExpr = RP.skipSpaces >> (pAbs RP.<++ pTerm)
e <- pExpr
return (foldr EAbs e xs)
pFactor = fmap EVar pCId
RP.<++ fmap ELit pLit
RP.<++ pMeta
pFactor = fmap EVar pCId
RP.<++ fmap ELit pLit
RP.<++ fmap EMeta pMeta
RP.<++ RP.between (RP.char '(') (RP.char ')') pExpr
where
pMeta = do RP.char '?'
n <- fmap read (RP.munch1 isDigit)
return (EMeta n)
pMeta = do RP.char '?'
cs <- RP.look
case cs of
(c:_) | isDigit c -> fmap read (RP.munch1 isDigit)
_ -> return 0
pLit :: RP.ReadP Literal
pLit = pNum RP.<++ liftM LStr pStr
@@ -166,7 +163,7 @@ ppTree d (Abs xs t) = ppParens (d > 0) (PP.char '\\' PP.<>
ppTree d (Fun f []) = PP.text (prCId f)
ppTree d (Fun f ts) = ppParens (d > 0) (PP.text (prCId f) PP.<+> PP.hsep (map (ppTree 1) ts))
ppTree d (Lit l) = ppLit l
ppTree d (Meta n) = PP.char '?' PP.<> PP.int n
ppTree d (Meta n) = ppMeta n
ppTree d (Var id) = PP.text (prCId id)
@@ -181,7 +178,7 @@ ppExpr d (EAbs x e) = let (xs,e1) = getVars (EAbs x e)
getVars e = ([],e)
ppExpr d (EApp e1 e2) = ppParens (d > 1) ((ppExpr 1 e1) PP.<+> (ppExpr 2 e2))
ppExpr d (ELit l) = ppLit l
ppExpr d (EMeta n) = PP.char '?' PP.<+> PP.int n
ppExpr d (EMeta n) = ppMeta n
ppExpr d (EVar f) = PP.text (prCId f)
ppPatt d (PApp f ps) = ppParens (d > 1) (PP.text (prCId f) PP.<+> PP.hsep (map (ppPatt 2) ps))
@@ -193,15 +190,20 @@ ppLit (LStr s) = PP.text (show s)
ppLit (LInt n) = PP.integer n
ppLit (LFlt d) = PP.double d
ppMeta n
| n == 0 = PP.char '?'
| otherwise = PP.char '?' PP.<> PP.int n
ppParens True = PP.parens
ppParens False = id
-----------------------------------------------------
-- Evaluation
-- Conversion Expr <-> Tree
-----------------------------------------------------
-- | Converts a tree to expression.
-- | Converts a tree to expression. The conversion
-- is always total, every tree is a valid expression.
tree2expr :: Tree -> Expr
tree2expr (Fun x ts) = foldl EApp (EVar x) (map tree2expr ts)
tree2expr (Lit l) = ELit l
@@ -209,29 +211,40 @@ tree2expr (Meta n) = EMeta n
tree2expr (Abs xs t) = foldr EAbs (tree2expr t) xs
tree2expr (Var x) = EVar x
-- | Converts an expression to tree. The expression
-- is first reduced to beta-eta-alfa normal form and
-- after that converted to tree.
expr2tree :: Funs -> Expr -> Tree
expr2tree funs e = value2tree [] (eval funs Map.empty e)
-- | Converts an expression to tree. The conversion is only partial.
-- Variables and meta variables of function type and beta redexes are not allowed.
expr2tree :: Expr -> Tree
expr2tree e = abs [] e
where
value2tree xs (VApp f vs) = case Map.lookup f funs of
Just (DTyp hyps _ _,_,_) -> -- eta conversion
let a1 = length hyps
a2 = length vs
a = a1 - a2
i = length xs
xs' = [var i | i <- [i..i+a-1]]
in ret (reverse xs'++xs)
(Fun f (map (value2tree []) vs++map Var xs'))
Nothing -> error ("unknown variable "++prCId f)
value2tree xs (VGen i vs) | null vs = ret xs (Var (var i))
| otherwise = error "variable of function type"
value2tree xs (VMeta n vs) | null vs = ret xs (Meta n)
| otherwise = error "meta variable of function type"
value2tree xs (VLit l) = ret xs (Lit l)
value2tree xs (VClosure env (EAbs x e)) = let i = length xs
in value2tree (var i:xs) (eval funs (Map.insert x (VGen i []) env) e)
abs xs (EAbs x e) = abs (x:xs) e
abs xs e = case xs of
[] -> app [] e
xs -> Abs (reverse xs) (app [] e)
app as (EApp e1 e2) = app ((abs [] e2) : as) e1
app as (ELit l)
| null as = Lit l
| otherwise = error "literal of function type encountered"
app as (EMeta n)
| null as = Meta n
| otherwise = error "meta variables of function type are not allowed in trees"
app as (EAbs x e) = error "beta redexes are not allowed in trees"
app as (EVar x) = Fun x as
-----------------------------------------------------
-- Computation
-----------------------------------------------------
-- | Compute an expression to normal form
normalForm :: Funs -> Expr -> Expr
normalForm funs e = value2expr 0 (eval funs Map.empty e)
where
value2expr i (VApp f vs) = foldl EApp (EVar f) (map (value2expr i) vs)
value2expr i (VGen j vs) = foldl EApp (EVar (var j)) (map (value2expr i) vs)
value2expr i (VMeta n vs) = foldl EApp (EMeta n) (map (value2expr i) vs)
value2expr i (VLit l) = ELit l
value2expr i (VClosure env (EAbs x e)) = EAbs (var i) (value2expr (i+1) (eval funs (Map.insert x (VGen i []) env) e))
var i = mkCId ('v':show i)

2
src/PGF/Paraphrase.hs
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@@ -49,7 +49,7 @@ fromDef pgf t@(Fun f ts) = defDown t ++ defUp t where
[(ps,p) | (p,d@(Fun g ps)) <- equs, g==f,
isClosed d || (length equs == 1 && isLinear d)]
equss = [(f,[(Fun f (map patt2tree ps), expr2tree (funs (abstract pgf)) d) | (Equ ps d) <- eqs]) |
equss = [(f,[(Fun f (map patt2tree ps), expr2tree d) | (Equ ps d) <- eqs]) |
(f,(_,_,eqs)) <- Map.assocs (funs (abstract pgf)), not (null eqs)]
trequ s f e = True ----trace (s ++ ": " ++ show f ++ " " ++ show e) True

6
src/PGF/TypeCheck.hs
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@@ -26,9 +26,9 @@ import Data.List (partition,sort,groupBy)
import Debug.Trace
typecheck :: PGF -> Tree -> [Tree]
typecheck pgf t = case inferExpr pgf (newMetas (tree2expr t)) of
Ok t -> [expr2tree (funs (abstract pgf)) t]
typecheck :: PGF -> Expr -> [Expr]
typecheck pgf e = case inferExpr pgf (newMetas e) of
Ok e -> [e]
Bad s -> trace s []
inferExpr :: PGF -> Expr -> Err Expr