cryptol-2.13.0: 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 BlockArguments #-}
{-# LANGUAGE Safe #-}
-- See Note [-Wincomplete-uni-patterns and irrefutable patterns] in Cryptol.TypeCheck.TypePat
{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
module Cryptol.TypeCheck.Infer
( checkE
, checkSigB
, inferModule
, inferBinds
, checkTopDecls
)
where
import Data.Text(Text)
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.Subst (listSubst,apSubst,(@@),isEmptySubst)
import Cryptol.TypeCheck.Unify(rootPath)
import Cryptol.Utils.Ident
import Cryptol.Utils.Panic(panic)
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,groupBy)
import Data.Either(partitionEithers)
import Data.Maybe(isJust, fromMaybe, mapMaybe)
import Data.List(partition)
import Data.Ratio(numerator,denominator)
import Data.Traversable(forM)
import Data.Function(on)
import Control.Monad(zipWithM,unless,foldM,forM_,mplus)
inferModule :: P.Module Name -> InferM Module
inferModule m =
do newModuleScope (thing (P.mName m)) (map thing (P.mImports m))
(P.modExports m)
checkTopDecls (P.mDecls m)
proveModuleTopLevel
endModule
-- | 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] -> TypeWithSource -> 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 ->
do (e1,ds1) <- checkLocalDecls ds (appTys e ts tGoal)
pure (EWhere e1 ds1)
P.ELocated e r ->
do e' <- inRange r (appTys e ts tGoal)
cs <- getCallStacks
if cs then pure (ELocated r e') else pure e'
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.EFromToBy {} -> mono
P.EFromToDownBy {} -> mono
P.EFromToLessThan {} -> 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 -> TypeWithSource -> 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 (twsType tGoal)
}
appTys e [arg] tGoal
P.ELit l -> (`checkE` tGoal) =<< desugarLiteral l
P.ETuple es ->
do etys <- expectTuple (length es) tGoal
let mkTGoal n t e = WithSource t (TypeOfTupleField n) (getLoc e)
es' <- zipWithM checkE es (zipWith3 mkTGoal [1..] etys es)
return (ETuple es')
P.ERecord fs ->
do es <- expectRec fs tGoal
let checkField f (e,t) =
checkE e (WithSource t (TypeOfRecordField f) (getLoc e))
es' <- traverseRecordMap checkField es
return (ERec es')
P.EUpd x fs -> checkRecUpd x fs tGoal
P.ESel e l ->
do let src = selSrc l
t <- newType src KType
e' <- checkE e (WithSource t src (getLoc expr))
f <- newHasGoal l t (twsType tGoal)
return (hasDoSelect f e')
P.EList [] ->
do (len,a) <- expectSeq tGoal
expectFin 0 (WithSource len LenOfSeq (getLoc expr))
return (EList [] a)
P.EList es ->
do (len,a) <- expectSeq tGoal
expectFin (length es) (WithSource len LenOfSeq (getLoc expr))
let checkElem e = checkE e (WithSource a TypeOfSeqElement (getLoc e))
es' <- mapM checkElem es
return (EList es' a)
P.EFromToBy isStrict t1 t2 t3 mety
| isStrict ->
do l <- curRange
let fs = [("first",t1),("bound",t2),("stride",t3)] ++
case mety of
Just ety -> [("a",ety)]
Nothing -> []
prim <- mkPrim "fromToByLessThan"
let e' = P.EAppT prim
[ P.NamedInst P.Named{ name = Located l (packIdent x), value = y }
| (x,y) <- fs
]
checkE e' tGoal
| otherwise ->
do l <- curRange
let fs = [("first",t1),("last",t2),("stride",t3)] ++
case mety of
Just ety -> [("a",ety)]
Nothing -> []
prim <- mkPrim "fromToBy"
let e' = P.EAppT prim
[ P.NamedInst P.Named{ name = Located l (packIdent x), value = y }
| (x,y) <- fs
]
checkE e' tGoal
P.EFromToDownBy isStrict t1 t2 t3 mety
| isStrict ->
do l <- curRange
let fs = [("first",t1),("bound",t2),("stride",t3)] ++
case mety of
Just ety -> [("a",ety)]
Nothing -> []
prim <- mkPrim "fromToDownByGreaterThan"
let e' = P.EAppT prim
[ P.NamedInst P.Named{ name = Located l (packIdent x), value = y }
| (x,y) <- fs
]
checkE e' tGoal
| otherwise ->
do l <- curRange
let fs = [("first",t1),("last",t2),("stride",t3)] ++
case mety of
Just ety -> [("a",ety)]
Nothing -> []
prim <- mkPrim "fromToDownBy"
let e' = P.EAppT prim
[ P.NamedInst P.Named{ name = Located l (packIdent x), value = y }
| (x,y) <- fs
]
checkE e' tGoal
P.EFromToLessThan t1 t2 mety ->
do l <- curRange
let fs0 =
case mety of
Just ety -> [("a", ety)]
Nothing -> []
let fs = [("first", t1), ("bound", t2)] ++ fs0
prim <- mkPrim "fromToLessThan"
let e' = P.EAppT prim
[ P.NamedInst P.Named { name = Located l (packIdent x), value = y }
| (x,y) <- fs
]
checkE e' tGoal
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
inferred <- smallest ts
ctrs <- unify (WithSource len LenOfSeq (getLoc expr)) inferred
newGoals CtComprehension ctrs
ds <- combineMaps dss
e' <- withMonoTypes ds (checkE e
(WithSource a TypeOfSeqElement (getLoc e)))
return (EComp len a e' mss')
where
-- the renamer should have made these checks already?
combineMaps ms = if null bad
then return (Map.unions ms)
else panic "combineMaps" $ "Multiple definitions"
: map show bad
where
bad = do m <- ms
duplicates [ a { thing = x } | (x,a) <- Map.toList m ]
duplicates = mapMaybe multiple
. groupBy ((==) `on` thing)
. sortBy (compare `on` thing)
where
multiple xs@(x : _ : _) = Just (thing x, map srcRange xs)
multiple _ = Nothing
P.EAppT e fs -> appTys e (map uncheckedTypeArg fs) tGoal
P.EApp e1 e2 ->
do let argSrc = TypeOfArg noArgDescr
t1 <- newType argSrc KType
e1' <- checkE e1
(WithSource (tFun t1 (twsType tGoal)) FunApp (getLoc e1))
e2' <- checkE e2 (WithSource t1 argSrc (getLoc e2))
return (EApp e1' e2')
P.EIf e1 e2 e3 ->
do e1' <- checkE e1 (WithSource tBit TypeOfIfCondExpr (getLoc e1))
e2' <- checkE e2 tGoal
e3' <- checkE e3 tGoal
return (EIf e1' e2' e3')
P.EWhere e ds ->
do (e1,ds1) <- checkLocalDecls ds (checkE e tGoal)
pure (EWhere e1 ds1)
P.ETyped e t ->
do tSig <- checkTypeOfKind t KType
e' <- checkE e (WithSource tSig TypeFromUserAnnotation (getLoc expr))
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 desc ps e -> checkFun desc ps e tGoal
P.ELocated e r ->
do e' <- inRange r (checkE e tGoal)
cs <- getCallStacks
if cs then pure (ELocated r e') else pure e'
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
checkRecUpd ::
Maybe (P.Expr Name) -> [ P.UpdField Name ] -> TypeWithSource -> InferM Expr
checkRecUpd mb fs tGoal =
case mb of
-- { _ | fs } ~~> \r -> { r | fs }
Nothing ->
do r <- newParamName NSValue (packIdent "r")
let p = P.PVar Located { srcRange = nameLoc r, thing = r }
fe = P.EFun P.emptyFunDesc [p] (P.EUpd (Just (P.EVar r)) fs)
checkE fe tGoal
Just e ->
do e1 <- checkE e tGoal
fst <$> foldM doUpd (e1, getLoc e) fs
where
doUpd (e,eloc) (P.UpdField how sels v) =
case sels of
[l] ->
case how of
P.UpdSet ->
do let src = selSrc s
ft <- newType src KType
v1 <- checkE v (WithSource ft src eloc)
d <- newHasGoal s (twsType tGoal) ft
pure (hasDoSet d e v1, eloc `rCombMaybe` getLoc v)
P.UpdFun ->
do let src = selSrc s
ft <- newType src KType
v1 <- checkE v (WithSource (tFun ft ft) src eloc)
-- XXX: ^ may be used a different src?
d <- newHasGoal s (twsType tGoal) ft
tmp <- newParamName NSValue (packIdent "rf")
let e' = EVar tmp
pure ( hasDoSet d e' (EApp v1 (hasDoSelect d e'))
`EWhere`
[ NonRecursive
Decl { dName = tmp
, dSignature = tMono (twsType tGoal)
, dDefinition = DExpr e
, dPragmas = []
, dInfix = False
, dFixity = Nothing
, dDoc = Nothing
} ]
, eloc `rCombMaybe` getLoc v )
where s = thing l
_ -> panic "checkRecUpd/doUpd" [ "Expected exactly 1 field label"
, "Got: " ++ show (length sels)
]
expectSeq :: TypeWithSource -> InferM (Type,Type)
expectSeq tGoal@(WithSource ty src rng) =
case ty of
TUser _ _ ty' ->
expectSeq (WithSource ty' src rng)
TCon (TC TCSeq) [a,b] ->
return (a,b)
TVar _ ->
do tys@(a,b) <- genTys
newGoals CtExactType =<< unify tGoal (tSeq a b)
return tys
_ ->
do tys@(a,b) <- genTys
recordErrorLoc rng (TypeMismatch src rootPath ty (tSeq a b))
return tys
where
genTys =
do a <- newType LenOfSeq KNum
b <- newType TypeOfSeqElement KType
return (a,b)
expectTuple :: Int -> TypeWithSource -> InferM [Type]
expectTuple n tGoal@(WithSource ty src rng) =
case ty of
TUser _ _ ty' ->
expectTuple n (WithSource ty' src rng)
TCon (TC (TCTuple n')) tys | n == n' ->
return tys
TVar _ ->
do tys <- genTys
newGoals CtExactType =<< unify tGoal (tTuple tys)
return tys
_ ->
do tys <- genTys
recordErrorLoc rng (TypeMismatch src rootPath ty (tTuple tys))
return tys
where
genTys =forM [ 0 .. n - 1 ] $ \ i -> newType (TypeOfTupleField i) KType
expectRec ::
RecordMap Ident (Range, a) ->
TypeWithSource ->
InferM (RecordMap Ident (a, Type))
expectRec fs tGoal@(WithSource ty src rng) =
case ty of
TUser _ _ ty' ->
expectRec fs (WithSource ty' src rng)
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 tGoal (TRec tys)
newGoals CtExactType ps
_ -> recordErrorLoc rng (TypeMismatch src rootPath ty (TRec tys))
return res
expectFin :: Int -> TypeWithSource -> InferM ()
expectFin n tGoal@(WithSource ty src rng) =
case ty of
TUser _ _ ty' ->
expectFin n (WithSource ty' src rng)
TCon (TC (TCNum n')) [] | toInteger n == n' ->
return ()
_ -> newGoals CtExactType =<< unify tGoal (tNum n)
expectFun :: Maybe Name -> Int -> TypeWithSource -> InferM ([Type],Type)
expectFun mbN n (WithSource ty0 src rng) = go [] n ty0
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 (WithSource ty src rng) (foldr tFun res args)
newGoals CtExactType ps
_ -> recordErrorLoc rng
(TypeMismatch src rootPath ty (foldr tFun res args))
return (reverse tys ++ args, res)
| otherwise =
return (reverse tys, ty)
genArgs arity = forM [ 1 .. arity ] $
\ ix -> newType (TypeOfArg (ArgDescr mbN (Just ix))) KType
checkHasType :: Type -> TypeWithSource -> InferM ()
checkHasType inferredType tGoal =
do ps <- unify tGoal inferredType
case ps of
[] -> return ()
_ -> newGoals CtExactType ps
checkFun ::
P.FunDesc Name -> [P.Pattern Name] ->
P.Expr Name -> TypeWithSource -> InferM Expr
checkFun _ [] e tGoal = checkE e tGoal
checkFun (P.FunDesc fun offset) ps e tGoal =
inNewScope
do let descs = [ TypeOfArg (ArgDescr fun (Just n)) | n <- [ 1 + offset .. ] ]
(tys,tRes) <- expectFun fun (length ps) tGoal
let srcs = zipWith3 WithSource tys descs (map getLoc ps)
largs <- sequence (zipWith checkP ps srcs)
let ds = Map.fromList [ (thing x, x { thing = t }) | (x,t) <- zip largs tys ]
e1 <- withMonoTypes ds
(checkE e (WithSource tRes TypeOfRes (twsRange tGoal)))
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 :: P.Pattern Name -> TypeWithSource -> InferM (Located Name)
checkP p tGoal@(WithSource _ src rng0) =
do (x, t) <- inferP p
ps <- unify tGoal (thing t)
let rngMb = getLoc p `mplus` rng0
rng = fromMaybe emptyRange rngMb
let mkErr = recordErrorLoc rngMb . UnsolvedGoals . (:[])
. Goal (CtPattern src) 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 :: P.Pattern Name -> InferM (Name, Located Type)
inferP 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 p (WithSource tSig TypeFromUserAnnotation (getLoc t))
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 p
n <- newType LenOfCompGen KNum
e' <- checkE e (WithSource (tSeq n (thing t)) GeneratorOfListComp
(getLoc e))
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 generalization.
-- 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 = TPUnifyVar
, 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 let nm = thing (P.bName b)
let tGoal = WithSource t (DefinitionOf nm) (getLoc b)
e1 <- checkFun (P.FunDesc (Just nm) 0) (P.bParams b) e tGoal
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 let nm = thing (P.bName b)
tGoal = WithSource t0 (DefinitionOf nm) (getLoc b)
e1 <- checkFun (P.FunDesc (Just nm) 0) (P.bParams b) e0 tGoal
addGoals validSchema
() <- simplifyAllConstraints -- XXX: using `asmps` also?
return e1
asmps1 <- applySubstPreds asmps0
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 -- if a goal mentions any of these variables, we'll commit to
-- solving it now.
stickyVars = Set.fromList (map tpVar as) `Set.union` fvs asmps1
(stay,leave) = findKeep stickyVars []
[ (c, fvs c) | c <- cs ]
addGoals leave
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
}
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
checkLocalDecls :: [P.Decl Name] -> InferM a -> InferM (a,[DeclGroup])
checkLocalDecls ds0 k =
do newLocalScope
forM_ ds0 \d -> checkDecl False d Nothing
a <- k
(ds,_tySyns) <- endLocalScope
pure (a,ds)
checkTopDecls :: [P.TopDecl Name] -> InferM ()
checkTopDecls = mapM_ checkTopDecl
where
checkTopDecl decl =
case decl of
P.Decl tl -> checkDecl True (P.tlValue tl) (thing <$> P.tlDoc tl)
P.TDNewtype tl ->
do t <- checkNewtype (P.tlValue tl) (thing <$> P.tlDoc tl)
addNewtype t
P.DPrimType tl ->
do t <- checkPrimType (P.tlValue tl) (thing <$> P.tlDoc tl)
addPrimType t
P.DParameterType ty ->
do t <- checkParameterType ty (P.ptDoc ty)
addParamType t
P.DParameterConstraint cs ->
do cs1 <- checkParameterConstraints cs
addParameterConstraints cs1
P.DParameterFun pf ->
do x <- checkParameterFun pf
addParamFun x
P.DModule tl ->
do let P.NestedModule m = P.tlValue tl
newSubmoduleScope (thing (P.mName m)) (map thing (P.mImports m))
(P.modExports m)
checkTopDecls (P.mDecls m)
endSubmodule
P.DImport {} -> pure ()
P.Include {} -> panic "checkTopDecl" [ "Unexpected `inlude`" ]
checkDecl :: Bool -> P.Decl Name -> Maybe Text -> InferM ()
checkDecl isTopLevel d mbDoc =
case d of
P.DBind c ->
do ~[b] <- inferBinds isTopLevel False [c]
addDecls (NonRecursive b)
P.DRec bs ->
do bs1 <- inferBinds isTopLevel True bs
addDecls (Recursive bs1)
P.DType t ->
do t1 <- checkTySyn t mbDoc
addTySyn t1
P.DProp t ->
do t1 <- checkPropSyn t mbDoc
addTySyn t1
P.DLocated d' r -> inRange r (checkDecl isTopLevel d' mbDoc)
P.DSignature {} -> bad "DSignature"
P.DFixity {} -> bad "DFixity"
P.DPragma {} -> bad "DPragma"
P.DPatBind {} -> bad "DPatBind"
where
bad x = panic "checkDecl" [x]
checkParameterFun :: P.ParameterFun Name -> InferM ModVParam
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
}
tcPanic :: String -> [String] -> a
tcPanic l msg = panic ("[TypeCheck] " ++ l) msg