cryptol-2.9.0: src/Cryptol/TypeCheck/Infer.hs
-- |
-- Module : Cryptol.TypeCheck.Infer
-- Copyright : (c) 2013-2016 Galois, Inc.
-- License : BSD3
-- Maintainer : cryptol@galois.com
-- Stability : provisional
-- Portability : portable
--
-- Assumes that the `NoPat` pass has been run.
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE PatternGuards #-}
{-# LANGUAGE ViewPatterns #-}
{-# LANGUAGE RecursiveDo #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE Safe #-}
module Cryptol.TypeCheck.Infer
( checkE
, checkSigB
, inferModule
, inferBinds
, inferDs
)
where
import qualified Data.Text as Text
import Cryptol.ModuleSystem.Name (lookupPrimDecl,nameLoc)
import Cryptol.Parser.Position
import qualified Cryptol.Parser.AST as P
import qualified Cryptol.ModuleSystem.Exports as P
import Cryptol.TypeCheck.AST hiding (tSub,tMul,tExp)
import Cryptol.TypeCheck.Monad
import Cryptol.TypeCheck.Error
import Cryptol.TypeCheck.Solve
import Cryptol.TypeCheck.SimpType(tMul)
import Cryptol.TypeCheck.Kind(checkType,checkSchema,checkTySyn,
checkPropSyn,checkNewtype,
checkParameterType,
checkPrimType,
checkParameterConstraints)
import Cryptol.TypeCheck.Instantiate
import Cryptol.TypeCheck.Depends
import Cryptol.TypeCheck.Subst (listSubst,apSubst,(@@),isEmptySubst)
import Cryptol.Utils.Ident
import Cryptol.Utils.Panic(panic)
import Cryptol.Utils.PP
import Cryptol.Utils.RecordMap
import qualified Data.Map as Map
import Data.Map (Map)
import qualified Data.Set as Set
import Data.List(foldl',sortBy)
import Data.Either(partitionEithers)
import Data.Maybe(mapMaybe,isJust, fromMaybe)
import Data.List(partition)
import Data.Graph(SCC(..))
import Data.Ratio(numerator,denominator)
import Data.Traversable(forM)
import Control.Monad(zipWithM,unless,foldM)
inferModule :: P.Module Name -> InferM Module
inferModule m =
inferDs (P.mDecls m) $ \ds1 ->
do proveModuleTopLevel
ts <- getTSyns
nts <- getNewtypes
ats <- getAbstractTypes
pTs <- getParamTypes
pCs <- getParamConstraints
pFuns <- getParamFuns
return Module { mName = thing (P.mName m)
, mExports = P.modExports m
, mImports = map thing (P.mImports m)
, mTySyns = Map.mapMaybe onlyLocal ts
, mNewtypes = Map.mapMaybe onlyLocal nts
, mPrimTypes = Map.mapMaybe onlyLocal ats
, mParamTypes = pTs
, mParamConstraints = pCs
, mParamFuns = pFuns
, mDecls = ds1
}
where
onlyLocal (IsLocal, x) = Just x
onlyLocal (IsExternal, _) = Nothing
-- | Construct a Prelude primitive in the parsed AST.
mkPrim :: String -> InferM (P.Expr Name)
mkPrim str =
do nm <- mkPrim' str
return (P.EVar nm)
-- | Construct a Prelude primitive in the parsed AST.
mkPrim' :: String -> InferM Name
mkPrim' str =
do prims <- getPrimMap
return (lookupPrimDecl (prelPrim (Text.pack str)) prims)
desugarLiteral :: P.Literal -> InferM (P.Expr Name)
desugarLiteral lit =
do l <- curRange
numberPrim <- mkPrim "number"
fracPrim <- mkPrim "fraction"
let named (x,y) = P.NamedInst
P.Named { name = Located l (packIdent x), value = y }
number fs = P.EAppT numberPrim (map named fs)
tBits n = P.TSeq (P.TNum n) P.TBit
return $ case lit of
P.ECNum num info ->
number $ [ ("val", P.TNum num) ] ++ case info of
P.BinLit n -> [ ("rep", tBits (1 * toInteger n)) ]
P.OctLit n -> [ ("rep", tBits (3 * toInteger n)) ]
P.HexLit n -> [ ("rep", tBits (4 * toInteger n)) ]
P.DecLit -> [ ]
P.PolyLit _n -> [ ("rep", P.TSeq P.TWild P.TBit) ]
P.ECFrac fr info ->
let arg f = P.PosInst (P.TNum (f fr))
rnd = P.PosInst (P.TNum (case info of
P.DecFrac -> 0
P.BinFrac -> 1
P.OctFrac -> 1
P.HexFrac -> 1))
in P.EAppT fracPrim [ arg numerator, arg denominator, rnd ]
P.ECChar c ->
number [ ("val", P.TNum (toInteger (fromEnum c)))
, ("rep", tBits (8 :: Integer)) ]
P.ECString s ->
P.ETyped (P.EList [ P.ELit (P.ECChar c) | c <- s ])
(P.TSeq P.TWild (P.TSeq (P.TNum 8) P.TBit))
-- | Infer the type of an expression with an explicit instantiation.
appTys :: P.Expr Name -> [TypeArg] -> Type -> InferM Expr
appTys expr ts tGoal =
case expr of
P.EVar x ->
do res <- lookupVar x
(e',t) <- case res of
ExtVar s -> instantiateWith x (EVar x) s ts
CurSCC e t -> do checkNoParams ts
return (e,t)
checkHasType t tGoal
return e'
P.ELit l -> do e <- desugarLiteral l
appTys e ts tGoal
P.EAppT e fs -> appTys e (map uncheckedTypeArg fs ++ ts) tGoal
-- Here is an example of why this might be useful:
-- f ` { x = T } where type T = ...
P.EWhere e ds ->
inferDs ds $ \ds1 -> do e1 <- appTys e ts tGoal
return (EWhere e1 ds1)
-- XXX: Is there a scoping issue here? I think not, but check.
P.ELocated e r ->
inRange r (appTys e ts tGoal)
P.ENeg {} -> mono
P.EComplement {} -> mono
P.EGenerate {} -> mono
P.ETuple {} -> mono
P.ERecord {} -> mono
P.EUpd {} -> mono
P.ESel {} -> mono
P.EList {} -> mono
P.EFromTo {} -> mono
P.EInfFrom {} -> mono
P.EComp {} -> mono
P.EApp {} -> mono
P.EIf {} -> mono
P.ETyped {} -> mono
P.ETypeVal {} -> mono
P.EFun {} -> mono
P.ESplit {} -> mono
P.EParens e -> appTys e ts tGoal
P.EInfix a op _ b -> appTys (P.EVar (thing op) `P.EApp` a `P.EApp` b) ts tGoal
where mono = do e' <- checkE expr tGoal
checkNoParams ts
return e'
checkNoParams :: [TypeArg] -> InferM ()
checkNoParams ts =
case pos of
p : _ -> do r <- case tyArgType p of
Unchecked t | Just r <- getLoc t -> pure r
_ -> curRange
inRange r (recordError TooManyPositionalTypeParams)
_ -> mapM_ badNamed named
where
badNamed l =
case tyArgName l of
Just i -> recordError (UndefinedTypeParameter i)
Nothing -> return ()
(named,pos) = partition (isJust . tyArgName) ts
checkTypeOfKind :: P.Type Name -> Kind -> InferM Type
checkTypeOfKind ty k = checkType ty (Just k)
-- | Infer the type of an expression, and translate it to a fully elaborated
-- core term.
checkE :: P.Expr Name -> Type -> InferM Expr
checkE expr tGoal =
case expr of
P.EVar x ->
do res <- lookupVar x
(e',t) <- case res of
ExtVar s -> instantiateWith x (EVar x) s []
CurSCC e t -> return (e, t)
checkHasType t tGoal
return e'
P.ENeg e ->
do prim <- mkPrim "negate"
checkE (P.EApp prim e) tGoal
P.EComplement e ->
do prim <- mkPrim "complement"
checkE (P.EApp prim e) tGoal
P.EGenerate e ->
do prim <- mkPrim "generate"
checkE (P.EApp prim e) tGoal
P.ELit l@(P.ECNum _ P.DecLit) ->
do e <- desugarLiteral l
-- NOTE: When 'l' is a decimal literal, 'desugarLiteral' does
-- not generate an instantiation for the 'rep' type argument
-- of the 'number' primitive. Therefore we explicitly
-- instantiate 'rep' to 'tGoal' in this case to avoid
-- generating an unnecessary unification variable.
loc <- curRange
let arg = TypeArg { tyArgName = Just (Located loc (packIdent "rep"))
, tyArgType = Checked tGoal
}
appTys e [arg] tGoal
P.ELit l -> (`checkE` tGoal) =<< desugarLiteral l
P.ETuple es ->
do etys <- expectTuple (length es) tGoal
es' <- zipWithM checkE es etys
return (ETuple es')
P.ERecord fs ->
do es <- expectRec fs tGoal
es' <- traverse (uncurry checkE) es
return (ERec es')
P.EUpd x fs -> checkRecUpd x fs tGoal
P.ESel e l ->
do t <- newType (selSrc l) KType
e' <- checkE e t
f <- newHasGoal l t tGoal
return (hasDoSelect f e')
P.EList [] ->
do (len,a) <- expectSeq tGoal
expectFin 0 len
return (EList [] a)
P.EList es ->
do (len,a) <- expectSeq tGoal
expectFin (length es) len
es' <- mapM (`checkE` a) es
return (EList es' a)
P.EFromTo t1 mbt2 t3 mety ->
do l <- curRange
let fs0 =
case mety of
Just ety -> [("a", ety)]
Nothing -> []
let (c,fs) =
case mbt2 of
Nothing ->
("fromTo", ("last", t3) : fs0)
Just t2 ->
("fromThenTo", ("next",t2) : ("last",t3) : fs0)
prim <- mkPrim c
let e' = P.EAppT prim
[ P.NamedInst P.Named { name = Located l (packIdent x), value = y }
| (x,y) <- ("first",t1) : fs
]
checkE e' tGoal
P.EInfFrom e1 Nothing ->
do prim <- mkPrim "infFrom"
checkE (P.EApp prim e1) tGoal
P.EInfFrom e1 (Just e2) ->
do prim <- mkPrim "infFromThen"
checkE (P.EApp (P.EApp prim e1) e2) tGoal
P.EComp e mss ->
do (mss', dss, ts) <- unzip3 `fmap` zipWithM inferCArm [ 1 .. ] mss
(len,a) <- expectSeq tGoal
newGoals CtComprehension =<< unify len =<< smallest ts
ds <- combineMaps dss
e' <- withMonoTypes ds (checkE e a)
return (EComp len a e' mss')
P.EAppT e fs -> appTys e (map uncheckedTypeArg fs) tGoal
P.EApp e1 e2 ->
do t1 <- newType (TypeOfArg Nothing) KType
e1' <- checkE e1 (tFun t1 tGoal)
e2' <- checkE e2 t1
return (EApp e1' e2')
P.EIf e1 e2 e3 ->
do e1' <- checkE e1 tBit
e2' <- checkE e2 tGoal
e3' <- checkE e3 tGoal
return (EIf e1' e2' e3')
P.EWhere e ds ->
inferDs ds $ \ds1 -> do e1 <- checkE e tGoal
return (EWhere e1 ds1)
P.ETyped e t ->
do tSig <- checkTypeOfKind t KType
e' <- checkE e tSig
checkHasType tSig tGoal
return e'
P.ETypeVal t ->
do l <- curRange
prim <- mkPrim "number"
checkE (P.EAppT prim
[P.NamedInst
P.Named { name = Located l (packIdent "val")
, value = t }]) tGoal
P.EFun ps e -> checkFun (text "anonymous function") ps e tGoal
P.ELocated e r -> inRange r (checkE e tGoal)
P.ESplit e ->
do prim <- mkPrim "splitAt"
checkE (P.EApp prim e) tGoal
P.EInfix a op _ b -> checkE (P.EVar (thing op) `P.EApp` a `P.EApp` b) tGoal
P.EParens e -> checkE e tGoal
selSrc :: P.Selector -> TVarSource
selSrc l = case l of
RecordSel la _ -> TypeOfRecordField la
TupleSel n _ -> TypeOfTupleField n
ListSel _ _ -> TypeOfSeqElement
checkRecUpd :: Maybe (P.Expr Name) -> [ P.UpdField Name ] -> Type -> InferM Expr
checkRecUpd mb fs tGoal =
case mb of
-- { _ | fs } ~~> \r -> { r | fs }
Nothing ->
do r <- newParamName (packIdent "r")
let p = P.PVar Located { srcRange = nameLoc r, thing = r }
fe = P.EFun [p] (P.EUpd (Just (P.EVar r)) fs)
checkE fe tGoal
Just e ->
do e1 <- checkE e tGoal
foldM doUpd e1 fs
where
doUpd e (P.UpdField how sels v) =
case sels of
[l] ->
case how of
P.UpdSet ->
do ft <- newType (selSrc s) KType
v1 <- checkE v ft
d <- newHasGoal s tGoal ft
pure (hasDoSet d e v1)
P.UpdFun ->
do ft <- newType (selSrc s) KType
v1 <- checkE v (tFun ft ft)
d <- newHasGoal s tGoal ft
tmp <- newParamName (packIdent "rf")
let e' = EVar tmp
pure $ hasDoSet d e' (EApp v1 (hasDoSelect d e'))
`EWhere`
[ NonRecursive
Decl { dName = tmp
, dSignature = tMono tGoal
, dDefinition = DExpr e
, dPragmas = []
, dInfix = False
, dFixity = Nothing
, dDoc = Nothing
} ]
where s = thing l
_ -> panic "checkRecUpd/doUpd" [ "Expected exactly 1 field label"
, "Got: " ++ show (length sels)
]
expectSeq :: Type -> InferM (Type,Type)
expectSeq ty =
case ty of
TUser _ _ ty' ->
expectSeq ty'
TCon (TC TCSeq) [a,b] ->
return (a,b)
TVar _ ->
do tys@(a,b) <- genTys
newGoals CtExactType =<< unify ty (tSeq a b)
return tys
_ ->
do tys@(a,b) <- genTys
recordError (TypeMismatch ty (tSeq a b))
return tys
where
genTys =
do a <- newType LenOfSeq KNum
b <- newType TypeOfSeqElement KType
return (a,b)
expectTuple :: Int -> Type -> InferM [Type]
expectTuple n ty =
case ty of
TUser _ _ ty' ->
expectTuple n ty'
TCon (TC (TCTuple n')) tys | n == n' ->
return tys
TVar _ ->
do tys <- genTys
newGoals CtExactType =<< unify ty (tTuple tys)
return tys
_ ->
do tys <- genTys
recordError (TypeMismatch ty (tTuple tys))
return tys
where
genTys =forM [ 0 .. n - 1 ] $ \ i -> newType (TypeOfTupleField i) KType
expectRec :: RecordMap Ident (Range, a) -> Type -> InferM (RecordMap Ident (a, Type))
expectRec fs ty =
case ty of
TUser _ _ ty' ->
expectRec fs ty'
TRec ls
| Right r <- zipRecords (\_ (_rng,v) t -> (v,t)) fs ls -> pure r
_ ->
do res <- traverseRecordMap
(\nm (_rng,v) ->
do t <- newType (TypeOfRecordField nm) KType
return (v, t))
fs
let tys = fmap snd res
case ty of
TVar TVFree{} -> do ps <- unify ty (TRec tys)
newGoals CtExactType ps
_ -> recordError (TypeMismatch ty (TRec tys))
return res
expectFin :: Int -> Type -> InferM ()
expectFin n ty =
case ty of
TUser _ _ ty' ->
expectFin n ty'
TCon (TC (TCNum n')) [] | toInteger n == n' ->
return ()
_ ->
do newGoals CtExactType =<< unify ty (tNum n)
expectFun :: Int -> Type -> InferM ([Type],Type)
expectFun = go []
where
go tys arity ty
| arity > 0 =
case ty of
TUser _ _ ty' ->
go tys arity ty'
TCon (TC TCFun) [a,b] ->
go (a:tys) (arity - 1) b
_ ->
do args <- genArgs arity
res <- newType TypeOfRes KType
case ty of
TVar TVFree{} -> do ps <- unify ty (foldr tFun res args)
newGoals CtExactType ps
_ -> recordError (TypeMismatch ty (foldr tFun res args))
return (reverse tys ++ args, res)
| otherwise =
return (reverse tys, ty)
genArgs arity = forM [ 1 .. arity ] $
\ ix -> newType (TypeOfArg (Just ix)) KType
checkHasType :: Type -> Type -> InferM ()
checkHasType inferredType givenType =
do ps <- unify givenType inferredType
case ps of
[] -> return ()
_ -> newGoals CtExactType ps
checkFun :: Doc -> [P.Pattern Name] -> P.Expr Name -> Type -> InferM Expr
checkFun _ [] e tGoal = checkE e tGoal
checkFun desc ps e tGoal =
inNewScope $
do let descs = [ text "type of" <+> ordinal n <+> text "argument"
<+> text "of" <+> desc | n <- [ 1 :: Int .. ] ]
(tys,tRes) <- expectFun (length ps) tGoal
largs <- sequence (zipWith3 checkP descs ps tys)
let ds = Map.fromList [ (thing x, x { thing = t }) | (x,t) <- zip largs tys ]
e1 <- withMonoTypes ds (checkE e tRes)
let args = [ (thing x, t) | (x,t) <- zip largs tys ]
return (foldr (\(x,t) b -> EAbs x t b) e1 args)
{-| The type the is the smallest of all -}
smallest :: [Type] -> InferM Type
smallest [] = newType LenOfSeq KNum
smallest [t] = return t
smallest ts = do a <- newType LenOfSeq KNum
newGoals CtComprehension [ a =#= foldr1 tMin ts ]
return a
checkP :: Doc -> P.Pattern Name -> Type -> InferM (Located Name)
checkP desc p tGoal =
do (x, t) <- inferP desc p
ps <- unify tGoal (thing t)
let rng = fromMaybe emptyRange $ getLoc p
let mkErr = recordError . UnsolvedGoals Nothing . (:[])
. Goal (CtPattern desc) rng
mapM_ mkErr ps
return (Located (srcRange t) x)
{-| Infer the type of a pattern. Assumes that the pattern will be just
a variable. -}
inferP :: Doc -> P.Pattern Name -> InferM (Name, Located Type)
inferP desc pat =
case pat of
P.PVar x0 ->
do a <- inRange (srcRange x0) (newType (DefinitionOf (thing x0)) KType)
return (thing x0, x0 { thing = a })
P.PTyped p t ->
do tSig <- checkTypeOfKind t KType
ln <- checkP desc p tSig
return (thing ln, ln { thing = tSig })
_ -> tcPanic "inferP" [ "Unexpected pattern:", show pat ]
-- | Infer the type of one match in a list comprehension.
inferMatch :: P.Match Name -> InferM (Match, Name, Located Type, Type)
inferMatch (P.Match p e) =
do (x,t) <- inferP (text "a value bound by a generator in a comprehension") p
n <- newType LenOfCompGen KNum
e' <- checkE e (tSeq n (thing t))
return (From x n (thing t) e', x, t, n)
inferMatch (P.MatchLet b)
| P.bMono b =
do let rng = srcRange (P.bName b)
a <- inRange rng (newType (DefinitionOf (thing (P.bName b))) KType)
b1 <- checkMonoB b a
return (Let b1, dName b1, Located (srcRange (P.bName b)) a, tNum (1::Int))
| otherwise = tcPanic "inferMatch"
[ "Unexpected polymorphic match let:", show b ]
-- | Infer the type of one arm of a list comprehension.
inferCArm :: Int -> [P.Match Name] -> InferM
( [Match]
, Map Name (Located Type)-- defined vars
, Type -- length of sequence
)
inferCArm _ [] = panic "inferCArm" [ "Empty comprehension arm" ]
inferCArm _ [m] =
do (m1, x, t, n) <- inferMatch m
return ([m1], Map.singleton x t, n)
inferCArm armNum (m : ms) =
do (m1, x, t, n) <- inferMatch m
(ms', ds, n') <- withMonoType (x,t) (inferCArm armNum ms)
newGoals CtComprehension [ pFin n' ]
return (m1 : ms', Map.insertWith (\_ old -> old) x t ds, tMul n n')
-- | @inferBinds isTopLevel isRec binds@ performs inference for a
-- strongly-connected component of 'P.Bind's.
-- If any of the members of the recursive group are already marked
-- as monomorphic, then we don't do generalzation.
-- If @isTopLevel@ is true,
-- any bindings without type signatures will be generalized. If it is
-- false, and the mono-binds flag is enabled, no bindings without type
-- signatures will be generalized, but bindings with signatures will
-- be unaffected.
inferBinds :: Bool -> Bool -> [P.Bind Name] -> InferM [Decl]
inferBinds isTopLevel isRec binds =
do -- when mono-binds is enabled, and we're not checking top-level
-- declarations, mark all bindings lacking signatures as monomorphic
monoBinds <- getMonoBinds
let (sigs,noSigs) = partition (isJust . P.bSignature) binds
monos = sigs ++ [ b { P.bMono = True } | b <- noSigs ]
binds' | any P.bMono binds = monos
| monoBinds && not isTopLevel = monos
| otherwise = binds
check exprMap =
{- Guess type is here, because while we check user supplied signatures
we may generate additional constraints. For example, `x - y` would
generate an additional constraint `x >= y`. -}
do (newEnv,todos) <- unzip `fmap` mapM (guessType exprMap) binds'
let otherEnv = filter isExt newEnv
let (sigsAndMonos,noSigGen) = partitionEithers todos
let prepGen = collectGoals
$ do bs <- sequence noSigGen
simplifyAllConstraints
return bs
if isRec
then
-- First we check the bindings with no signatures
-- that need to be generalized.
do (bs1,cs) <- withVarTypes newEnv prepGen
-- We add these to the environment, so their fvs are
-- not generalized.
genCs <- withVarTypes otherEnv (generalize bs1 cs)
-- Then we do all the rest,
-- using the newly inferred poly types.
let newEnv' = map toExt bs1 ++ otherEnv
done <- withVarTypes newEnv' (sequence sigsAndMonos)
return (done,genCs)
else
do done <- sequence sigsAndMonos
(bs1, cs) <- prepGen
genCs <- generalize bs1 cs
return (done,genCs)
rec
let exprMap = Map.fromList (map monoUse genBs)
(doneBs, genBs) <- check exprMap
simplifyAllConstraints
return (doneBs ++ genBs)
where
toExt d = (dName d, ExtVar (dSignature d))
isExt (_,y) = case y of
ExtVar _ -> True
_ -> False
monoUse d = (x, withQs)
where
x = dName d
as = sVars (dSignature d)
qs = sProps (dSignature d)
appT e a = ETApp e (TVar (tpVar a))
appP e _ = EProofApp e
withTys = foldl' appT (EVar x) as
withQs = foldl' appP withTys qs
{- | Come up with a type for recursive calls to a function, and decide
how we are going to be checking the binding.
Returns: (Name, type or schema, computation to check binding)
The `exprMap` is a thunk where we can lookup the final expressions
and we should be careful not to force it.
-}
guessType :: Map Name Expr -> P.Bind Name ->
InferM ( (Name, VarType)
, Either (InferM Decl) -- no generalization
(InferM Decl) -- generalize these
)
guessType exprMap b@(P.Bind { .. }) =
case bSignature of
Just s ->
do s1 <- checkSchema AllowWildCards s
return ((name, ExtVar (fst s1)), Left (checkSigB b s1))
Nothing
| bMono ->
do t <- newType (DefinitionOf name) KType
let schema = Forall [] [] t
return ((name, ExtVar schema), Left (checkMonoB b t))
| otherwise ->
do t <- newType (DefinitionOf name) KType
let noWay = tcPanic "guessType" [ "Missing expression for:" ,
show name ]
expr = Map.findWithDefault noWay name exprMap
return ((name, CurSCC expr t), Right (checkMonoB b t))
where
name = thing bName
{- | The inputs should be declarations with monomorphic types
(i.e., of the form `Forall [] [] t`). -}
generalize :: [Decl] -> [Goal] -> InferM [Decl]
{- This may happen because we have monomorphic bindings.
In this case we may get some goal, due to the monomorphic bindings,
but the group of components is empty. -}
generalize [] gs0 =
do addGoals gs0
return []
generalize bs0 gs0 =
do {- First, we apply the accumulating substitution to the goals
and the inferred types, to ensure that we have the most up
to date information. -}
gs <- applySubstGoals gs0
bs <- forM bs0 $ \b -> do s <- applySubst (dSignature b)
return b { dSignature = s }
-- Next, we figure out which of the free variables need to be generalized
-- Variables apearing in the types of monomorphic bindings should
-- not be generalizedr.
let goalFVS g = Set.filter isFreeTV $ fvs $ goal g
inGoals = Set.unions $ map goalFVS gs
inSigs = Set.filter isFreeTV $ fvs $ map dSignature bs
candidates = (Set.union inGoals inSigs)
asmpVs <- varsWithAsmps
let gen0 = Set.difference candidates asmpVs
stays g = any (`Set.member` gen0) $ Set.toList $ goalFVS g
(here0,later) = partition stays gs
addGoals later -- these ones we keep around for to solve later
let maybeAmbig = Set.toList (Set.difference gen0 inSigs)
{- See if we might be able to default some of the potentially ambiguous
variables using the constraints that will be part of the newly
generalized schema. -}
let (as0,here1,defSu,ws,errs) = defaultAndSimplify maybeAmbig here0
extendSubst defSu
mapM_ recordWarning ws
mapM_ recordError errs
let here = map goal here1
{- This is the variables we'll be generalizing:
* any ones that survived the defaulting
* and vars in the inferred types that do not appear anywhere else. -}
let as = sortBy numFst
$ as0 ++ Set.toList (Set.difference inSigs asmpVs)
asPs = [ TParam { tpUnique = x, tpKind = k, tpFlav = TPOther Nothing
, tpInfo = i } | TVFree x k _ i <- as ]
{- Finally, we replace free variables with bound ones, and fix-up
the definitions as needed to reflect that we are now working
with polymorphic things. For example, apply each occurrence to the
type parameters. -}
totSu <- getSubst
let
su = listSubst (zip as (map (TVar . tpVar) asPs)) @@ totSu
qs = concatMap (pSplitAnd . apSubst su) here
genE e = foldr ETAbs (foldr EProofAbs (apSubst su e) qs) asPs
genB d = d { dDefinition = case dDefinition d of
DExpr e -> DExpr (genE e)
DPrim -> DPrim
, dSignature = Forall asPs qs
$ apSubst su $ sType $ dSignature d
}
return (map genB bs)
where
numFst x y = case (kindOf x, kindOf y) of
(KNum, KNum) -> EQ
(KNum, _) -> LT
(_,KNum) -> GT
_ -> EQ
-- | Check a monomorphic binding.
checkMonoB :: P.Bind Name -> Type -> InferM Decl
checkMonoB b t =
inRangeMb (getLoc b) $
case thing (P.bDef b) of
P.DPrim -> panic "checkMonoB" ["Primitive with no signature?"]
P.DExpr e ->
do e1 <- checkFun (pp (thing (P.bName b))) (P.bParams b) e t
let f = thing (P.bName b)
return Decl { dName = f
, dSignature = Forall [] [] t
, dDefinition = DExpr e1
, dPragmas = P.bPragmas b
, dInfix = P.bInfix b
, dFixity = P.bFixity b
, dDoc = P.bDoc b
}
-- XXX: Do we really need to do the defaulting business in two different places?
checkSigB :: P.Bind Name -> (Schema,[Goal]) -> InferM Decl
checkSigB b (Forall as asmps0 t0, validSchema) = case thing (P.bDef b) of
-- XXX what should we do with validSchema in this case?
P.DPrim ->
do return Decl { dName = thing (P.bName b)
, dSignature = Forall as asmps0 t0
, dDefinition = DPrim
, dPragmas = P.bPragmas b
, dInfix = P.bInfix b
, dFixity = P.bFixity b
, dDoc = P.bDoc b
}
P.DExpr e0 ->
inRangeMb (getLoc b) $
withTParams as $
do (e1,cs0) <- collectGoals $
do e1 <- checkFun (pp (thing (P.bName b))) (P.bParams b) e0 t0
addGoals validSchema
() <- simplifyAllConstraints -- XXX: using `asmps` also?
return e1
cs <- applySubstGoals cs0
let findKeep vs keep todo =
let stays (_,cvs) = not $ Set.null $ Set.intersection vs cvs
(yes,perhaps) = partition stays todo
(stayPs,newVars) = unzip yes
in case stayPs of
[] -> (keep,map fst todo)
_ -> findKeep (Set.unions (vs:newVars)) (stayPs ++ keep) perhaps
let (stay,leave) = findKeep (Set.fromList (map tpVar as)) []
[ (c, fvs c) | c <- cs ]
addGoals leave
asmps1 <- applySubstPreds asmps0
su <- proveImplication (Just (thing (P.bName b))) as asmps1 stay
extendSubst su
let asmps = concatMap pSplitAnd (apSubst su asmps1)
t <- applySubst t0
e2 <- applySubst e1
return Decl
{ dName = thing (P.bName b)
, dSignature = Forall as asmps t
, dDefinition = DExpr (foldr ETAbs (foldr EProofAbs e2 asmps) as)
, dPragmas = P.bPragmas b
, dInfix = P.bInfix b
, dFixity = P.bFixity b
, dDoc = P.bDoc b
}
inferDs :: FromDecl d => [d] -> ([DeclGroup] -> InferM a) -> InferM a
inferDs ds continue = checkTyDecls =<< orderTyDecls (mapMaybe toTyDecl ds)
where
isTopLevel = isTopDecl (head ds)
checkTyDecls (AT t mbD : ts) =
do t1 <- checkParameterType t mbD
withParamType t1 (checkTyDecls ts)
checkTyDecls (TS t mbD : ts) =
do t1 <- checkTySyn t mbD
withTySyn t1 (checkTyDecls ts)
checkTyDecls (PS t mbD : ts) =
do t1 <- checkPropSyn t mbD
withTySyn t1 (checkTyDecls ts)
checkTyDecls (NT t mbD : ts) =
do t1 <- checkNewtype t mbD
withNewtype t1 (checkTyDecls ts)
checkTyDecls (PT p mbD : ts) =
do p1 <- checkPrimType p mbD
withPrimType p1 (checkTyDecls ts)
-- We checked all type synonyms, now continue with value-level definitions:
checkTyDecls [] =
do cs <- checkParameterConstraints (concatMap toParamConstraints ds)
withParameterConstraints cs $
do xs <- mapM checkParameterFun (mapMaybe toParamFun ds)
withParamFuns xs $ checkBinds [] $ orderBinds $ mapMaybe toBind ds
checkParameterFun x =
do (s,gs) <- checkSchema NoWildCards (P.pfSchema x)
su <- proveImplication (Just (thing (P.pfName x)))
(sVars s) (sProps s) gs
unless (isEmptySubst su) $
panic "checkParameterFun" ["Subst not empty??"]
let n = thing (P.pfName x)
return ModVParam { mvpName = n
, mvpType = s
, mvpDoc = P.pfDoc x
, mvpFixity = P.pfFixity x
}
checkBinds decls (CyclicSCC bs : more) =
do bs1 <- inferBinds isTopLevel True bs
foldr (\b m -> withVar (dName b) (dSignature b) m)
(checkBinds (Recursive bs1 : decls) more)
bs1
checkBinds decls (AcyclicSCC c : more) =
do ~[b] <- inferBinds isTopLevel False [c]
withVar (dName b) (dSignature b) $
checkBinds (NonRecursive b : decls) more
-- We are done with all value-level definitions.
-- Now continue with anything that's in scope of the declarations.
checkBinds decls [] = continue (reverse decls)
tcPanic :: String -> [String] -> a
tcPanic l msg = panic ("[TypeCheck] " ++ l) msg