TcBinds.hs 74.8 KB
 Austin Seipp committed Dec 03, 2014 1 2 3 4 {- (c) The University of Glasgow 2006 (c) The GRASP/AQUA Project, Glasgow University, 1992-1998  partain committed Jan 08, 1996 5 \section[TcBinds]{TcBinds}  Austin Seipp committed Dec 03, 2014 6 -}  partain committed Jan 08, 1996 7   Herbert Valerio Riedel committed May 15, 2014 8 9 {-# LANGUAGE CPP, RankNTypes, ScopedTypeVariables #-}  Simon Peyton Jones committed Nov 29, 2011 10 module TcBinds ( tcLocalBinds, tcTopBinds, tcRecSelBinds,  Simon Peyton Jones committed Sep 17, 2012 11  tcHsBootSigs, tcPolyCheck,  Simon Peyton Jones committed Jan 14, 2015 12 13 14  PragFun, tcSpecPrags, tcSpecWrapper, tcVectDecls, TcSigInfo(..), TcSigFun, mkPragFun,  Simon Peyton Jones committed Mar 07, 2014 15  instTcTySig, instTcTySigFromId, findScopedTyVars,  Facundo Domínguez committed Dec 09, 2014 16  badBootDeclErr, mkExport ) where  partain committed Jan 08, 1996 17   ross committed Sep 20, 2003 18 import {-# SOURCE #-} TcMatches ( tcGRHSsPat, tcMatchesFun )  simonpj@microsoft.com committed Jan 25, 2006 19 import {-# SOURCE #-} TcExpr ( tcMonoExpr )  Simon Peyton Jones committed Nov 21, 2014 20 import {-# SOURCE #-} TcPatSyn ( tcInferPatSynDecl, tcCheckPatSynDecl, tcPatSynBuilderBind )  Simon Marlow committed Oct 11, 2006 21 22 import DynFlags import HsSyn  Edward Z. Yang committed Oct 24, 2014 23 import HscTypes( isHsBootOrSig )  simonpj committed Sep 13, 2002 24 import TcRnMonad  Simon Marlow committed Oct 11, 2006 25 26 27 import TcEnv import TcUnify import TcSimplify  Simon Peyton Jones committed Dec 05, 2011 28 import TcEvidence  Simon Marlow committed Oct 11, 2006 29 30 31 import TcHsType import TcPat import TcMType  cactus committed Jan 20, 2014 32 import ConLike  Simon Peyton Jones committed Jan 14, 2015 33 import Inst( deeplyInstantiate )  Simon Peyton Jones committed Nov 04, 2014 34 35 import FamInstEnv( normaliseType ) import FamInst( tcGetFamInstEnvs )  thomasw committed Nov 28, 2014 36 import Type( pprSigmaTypeExtraCts )  chak@cse.unsw.edu.au. committed Aug 19, 2011 37 import TyCon  Simon Marlow committed Oct 11, 2006 38 39 40 import TcType import TysPrim import Id  41 import Var  Simon Peyton Jones committed Aug 16, 2011 42 import VarSet  Simon Peyton Jones committed Jun 11, 2014 43 import VarEnv( TidyEnv )  ian@well-typed.com committed Nov 02, 2012 44 import Module  Simon Marlow committed Oct 11, 2006 45 import Name  simonpj committed May 18, 1999 46 import NameSet  simonpj committed Jul 19, 2005 47 import NameEnv  Simon Marlow committed Oct 11, 2006 48 import SrcLoc  simonm committed Dec 02, 1998 49 import Bag  chak@cse.unsw.edu.au. committed Feb 20, 2011 50 import ListSetOps  Simon Marlow committed Oct 11, 2006 51 52 53 54 55 import ErrUtils import Digraph import Maybes import Util import BasicTypes  simonm committed Jan 08, 1998 56 import Outputable  Ian Lynagh committed Mar 29, 2008 57 import FastString  Simon Peyton Jones committed Jun 13, 2012 58 59 import Type(mkStrLitTy) import PrelNames(ipClassName)  Simon Peyton Jones committed Jun 11, 2014 60 import TcValidity (checkValidType)  twanvl committed Jan 17, 2008 61 62  import Control.Monad  cactus committed Nov 20, 2014 63 import Data.List (partition)  simonpj@microsoft.com committed Oct 07, 2010 64 65  #include "HsVersions.h"  simonpj committed Mar 14, 1997 66   Austin Seipp committed Dec 03, 2014 67 68 69 {- ************************************************************************ * *  partain committed Jan 08, 1996 70 \subsection{Type-checking bindings}  Austin Seipp committed Dec 03, 2014 71 72 * * ************************************************************************  partain committed Jan 08, 1996 73   partain committed Mar 19, 1996 74 @tcBindsAndThen@ typechecks a @HsBinds@. The "and then" part is because  partain committed Jan 08, 1996 75 76 77 78 79 80 81 82 83 84 it needs to know something about the {\em usage} of the things bound, so that it can create specialisations of them. So @tcBindsAndThen@ takes a function which, given an extended environment, E, typechecks the scope of the bindings returning a typechecked thing and (most important) an LIE. It is this LIE which is then used as the basis for specialising the things bound. @tcBindsAndThen@ also takes a "combiner" which glues together the bindings and the "thing" to make a new "thing".  simonpj committed Mar 14, 1997 85 The real work is done by @tcBindWithSigsAndThen@.  partain committed Jan 08, 1996 86 87 88 89 90 91 92 93 94 95  Recursive and non-recursive binds are handled in essentially the same way: because of uniques there are no scoping issues left. The only difference is that non-recursive bindings can bind primitive values. Even for non-recursive binding groups we add typings for each binder to the LVE for the following reason. When each individual binding is checked the type of its LHS is unified with that of its RHS; and type-checking the LHS of course requires that the binder is in scope.  partain committed Mar 19, 1996 96 97 98 At the top-level the LIE is sure to contain nothing but constant dictionaries, which we resolve at the module level.  Simon Peyton Jones committed Mar 02, 2012 99 100 Note [Polymorphic recursion] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~  cactus committed Nov 20, 2014 101 The game plan for polymorphic recursion in the code above is  Simon Peyton Jones committed Mar 02, 2012 102 103  * Bind any variable for which we have a type signature  cactus committed Nov 20, 2014 104  to an Id with a polymorphic type. Then when type-checking  Simon Peyton Jones committed Mar 02, 2012 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156  the RHSs we'll make a full polymorphic call. This fine, but if you aren't a bit careful you end up with a horrendous amount of partial application and (worse) a huge space leak. For example: f :: Eq a => [a] -> [a] f xs = ...f... If we don't take care, after typechecking we get f = /\a -> \d::Eq a -> let f' = f a d in \ys:[a] -> ...f'... Notice the the stupid construction of (f a d), which is of course identical to the function we're executing. In this case, the polymorphic recursion isn't being used (but that's a very common case). This can lead to a massive space leak, from the following top-level defn (post-typechecking) ff :: [Int] -> [Int] ff = f Int dEqInt Now (f dEqInt) evaluates to a lambda that has f' as a free variable; but f' is another thunk which evaluates to the same thing... and you end up with a chain of identical values all hung onto by the CAF ff. ff = f Int dEqInt = let f' = f Int dEqInt in \ys. ...f'... = let f' = let f' = f Int dEqInt in \ys. ...f'... in \ys. ...f'... Etc. NOTE: a bit of arity anaysis would push the (f a d) inside the (\ys...), which would make the space leak go away in this case Solution: when typechecking the RHSs we always have in hand the *monomorphic* Ids for each binding. So we just need to make sure that if (Method f a d) shows up in the constraints emerging from (...f...) we just use the monomorphic Id. We achieve this by adding monomorphic Ids to the "givens" when simplifying constraints. That's what the "lies_avail" is doing. Then we get f = /\a -> \d::Eq a -> letrec fm = \ys:[a] -> ...fm... in fm  Austin Seipp committed Dec 03, 2014 157 -}  Simon Peyton Jones committed Mar 02, 2012 158   Simon Peyton Jones committed Nov 29, 2011 159 160 161 162 tcTopBinds :: HsValBinds Name -> TcM (TcGblEnv, TcLclEnv) -- The TcGblEnv contains the new tcg_binds and tcg_spects -- The TcLclEnv has an extended type envt for the new bindings tcTopBinds (ValBindsOut binds sigs)  cactus committed Jan 20, 2014 163 164 165 166 167  = do { -- Pattern synonym bindings populate the global environment (binds', (tcg_env, tcl_env)) <- tcValBinds TopLevel binds sigs $do { gbl <- getGblEnv ; lcl <- getLclEnv ; return (gbl, lcl) }  Simon Peyton Jones committed Nov 29, 2011 168 169 170 171 172 173 174 175  ; specs <- tcImpPrags sigs -- SPECIALISE prags for imported Ids ; let { tcg_env' = tcg_env { tcg_binds = foldr (unionBags . snd) (tcg_binds tcg_env) binds' , tcg_imp_specs = specs ++ tcg_imp_specs tcg_env } } ; return (tcg_env', tcl_env) }  cactus committed Nov 20, 2014 176  -- The top level bindings are flattened into a giant  Ian Lynagh committed May 18, 2008 177  -- implicitly-mutually-recursive LHsBinds  cactus committed Jan 20, 2014 178   Simon Peyton Jones committed Nov 29, 2011 179 180 181 182 183 184 tcTopBinds (ValBindsIn {}) = panic "tcTopBinds" tcRecSelBinds :: HsValBinds Name -> TcM TcGblEnv tcRecSelBinds (ValBindsOut binds sigs) = tcExtendGlobalValEnv [sel_id | L _ (IdSig sel_id) <- sigs]$ do { (rec_sel_binds, tcg_env) <- discardWarnings (tcValBinds TopLevel binds sigs getGblEnv)  cactus committed Nov 20, 2014 185  ; let tcg_env'  Edward Z. Yang committed Oct 24, 2014 186  | isHsBootOrSig (tcg_src tcg_env) = tcg_env  Simon Peyton Jones committed Nov 29, 2011 187 188 189  | otherwise = tcg_env { tcg_binds = foldr (unionBags . snd) (tcg_binds tcg_env) rec_sel_binds }  cactus committed Nov 20, 2014 190  -- Do not add the code for record-selector bindings when  Simon Peyton Jones committed Nov 29, 2011 191 192 193  -- compiling hs-boot files ; return tcg_env' } tcRecSelBinds (ValBindsIn {}) = panic "tcRecSelBinds"  simonpj committed Oct 13, 2000 194   simonpj committed Jul 19, 2005 195 tcHsBootSigs :: HsValBinds Name -> TcM [Id]  simonpj committed Jan 27, 2005 196 197 -- A hs-boot file has only one BindGroup, and it only has type -- signatures in it. The renamer checked all this  simonpj committed Aug 11, 2005 198 tcHsBootSigs (ValBindsOut binds sigs)  Ian Lynagh committed May 18, 2008 199  = do { checkTc (null binds) badBootDeclErr  waern committed Jun 10, 2011 200  ; concat <$> mapM (addLocM tc_boot_sig) (filter isTypeLSig sigs) }  simonpj committed Jan 27, 2005 201  where  thomasw committed Nov 28, 2014 202  tc_boot_sig (TypeSig lnames ty _) = mapM f lnames  waern committed Jun 10, 2011 203  where  Simon Peyton Jones committed Jan 06, 2015 204  f (L _ name) = do { sigma_ty <- tcHsSigType (FunSigCtxt name True) ty  waern committed Jun 10, 2011 205  ; return (mkVanillaGlobal name sigma_ty) }  Ian Lynagh committed May 18, 2008 206  -- Notice that we make GlobalIds, not LocalIds  Ian Lynagh committed May 18, 2008 207  tc_boot_sig s = pprPanic "tcHsBootSigs/tc_boot_sig" (ppr s)  simonpj committed Jul 12, 2005 208 tcHsBootSigs groups = pprPanic "tcHsBootSigs" (ppr groups)  simonpj committed Oct 13, 2000 209   Simon Peyton Jones committed Jan 12, 2012 210 badBootDeclErr :: MsgDoc  Ian Lynagh committed Apr 12, 2008 211 badBootDeclErr = ptext (sLit "Illegal declarations in an hs-boot file")  simonpj committed May 03, 2005 212   simonpj committed Jul 19, 2005 213 214 ------------------------ tcLocalBinds :: HsLocalBinds Name -> TcM thing  Ian Lynagh committed May 18, 2008 215  -> TcM (HsLocalBinds TcId, thing)  sof committed May 18, 1997 216   cactus committed Nov 20, 2014 217 tcLocalBinds EmptyLocalBinds thing_inside  Ian Lynagh committed May 18, 2008 218 219  = do { thing <- thing_inside ; return (EmptyLocalBinds, thing) }  sof committed May 18, 1997 220   Simon Peyton Jones committed Nov 29, 2011 221 222 223 224 tcLocalBinds (HsValBinds (ValBindsOut binds sigs)) thing_inside = do { (binds', thing) <- tcValBinds NotTopLevel binds sigs thing_inside ; return (HsValBinds (ValBindsOut binds' sigs), thing) } tcLocalBinds (HsValBinds (ValBindsIn {})) _ = panic "tcLocalBinds"  simonm committed Jan 08, 1998 225   simonpj committed Jul 19, 2005 226 tcLocalBinds (HsIPBinds (IPBinds ip_binds _)) thing_inside  Simon Peyton Jones committed Jun 13, 2012 227 228 229  = do { ipClass <- tcLookupClass ipClassName ; (given_ips, ip_binds') <- mapAndUnzipM (wrapLocSndM (tc_ip_bind ipClass)) ip_binds  simonpj committed Oct 23, 2002 230   cactus committed Nov 20, 2014 231  -- If the binding binds ?x = E, we must now  Ian Lynagh committed May 18, 2008 232  -- discharge any ?x constraints in expr_lie  simonpj@microsoft.com committed Oct 21, 2010 233  -- See Note [Implicit parameter untouchables]  cactus committed Nov 20, 2014 234  ; (ev_binds, result) <- checkConstraints (IPSkol ips)  simonpj@microsoft.com committed Oct 21, 2010 235  [] given_ips thing_inside  simonpj@microsoft.com committed Sep 13, 2010 236 237  ; return (HsIPBinds (IPBinds ip_binds' ev_binds), result) }  simonpj committed Oct 23, 2002 238  where  Alan Zimmerman committed Jan 16, 2015 239  ips = [ip | L _ (IPBind (Left (L _ ip)) _) <- ip_binds]  simonpj@microsoft.com committed Sep 13, 2010 240   Ian Lynagh committed May 18, 2008 241 242 243  -- I wonder if we should do these one at at time -- Consider ?x = 4 -- ?y = ?x + 1  Alan Zimmerman committed Jan 16, 2015 244  tc_ip_bind ipClass (IPBind (Left (L _ ip)) expr)  batterseapower committed May 15, 2012 245  = do { ty <- newFlexiTyVarTy openTypeKind  Simon Peyton Jones committed Jun 13, 2012 246 247  ; let p = mkStrLitTy$ hsIPNameFS ip ; ip_id <- newDict ipClass [ p, ty ]  simonpj@microsoft.com committed Sep 13, 2010 248  ; expr' <- tcMonoExpr expr ty  Simon Peyton Jones committed Jun 13, 2012 249 250 251 252 253 254  ; let d = toDict ipClass p ty fmap expr' ; return (ip_id, (IPBind (Right ip_id) d)) } tc_ip_bind _ (IPBind (Right {}) _) = panic "tc_ip_bind" -- Coerces a t into a dictionry for IP "x" t. -- co : t -> IP "x" t  Eric Seidel committed Jan 19, 2015 255 256  toDict ipClass x ty = HsWrap $mkWpCast$ TcCoercion $wrapIP$ mkClassPred ipClass [x,ty]  Simon Peyton Jones committed Jun 13, 2012 257   Austin Seipp committed Dec 03, 2014 258 {-  simonpj@microsoft.com committed Sep 17, 2010 259 260 261 262 263 264 265 Note [Implicit parameter untouchables] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We add the type variables in the types of the implicit parameters as untouchables, not so much because we really must not unify them, but rather because we otherwise end up with constraints like this Num alpha, Implic { wanted = alpha ~ Int } The constraint solver solves alpha~Int by unification, but then  cactus committed Nov 20, 2014 266 doesn't float that solved constraint out (it's not an unsolved  Simon Peyton Jones committed Aug 16, 2011 267 wanted). Result disaster: the (Num alpha) is again solved, this  simonpj@microsoft.com committed Sep 17, 2010 268 269 time by defaulting. No no no.  cactus committed Nov 20, 2014 270 However [Oct 10] this is all handled automatically by the  simonpj@microsoft.com committed Oct 21, 2010 271 272 untouchable-range idea.  Simon Peyton Jones committed Jun 24, 2014 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 Note [Placeholder PatSyn kinds] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider this (Trac #9161) {-# LANGUAGE PatternSynonyms, DataKinds #-} pattern A = () b :: A b = undefined Here, the type signature for b mentions A. But A is a pattern synonym, which is typechecked (for very good reasons; a view pattern in the RHS may mention a value binding) as part of a group of bindings. It is entirely resonable to reject this, but to do so we need A to be in the kind environment when kind-checking the signature for B. Hence the tcExtendKindEnv2 patsyn_placeholder_kinds, which adds a binding A -> AGlobal (AConLike (PatSynCon _|_)) to the environment. Then TcHsType.tcTyVar will find A in the kind environment, and will give a 'wrongThingErr' as a result. But the lookup of A won't fail. The _|_ (= panic "fakePatSynCon") works because the wrongThingErr call, in tcTyVar, doesn't look inside the TcTyThing.  Austin Seipp committed Dec 03, 2014 295 -}  Simon Peyton Jones committed Jun 24, 2014 296   cactus committed Nov 20, 2014 297 tcValBinds :: TopLevelFlag  Simon Peyton Jones committed Nov 29, 2011 298 299  -> [(RecFlag, LHsBinds Name)] -> [LSig Name] -> TcM thing  cactus committed Nov 20, 2014 300  -> TcM ([(RecFlag, LHsBinds TcId)], thing)  simonpj committed Oct 27, 2005 301   Simon Peyton Jones committed Nov 29, 2011 302 tcValBinds top_lvl binds sigs thing_inside  Simon Peyton Jones committed Jun 24, 2014 303  = do { -- Typecheck the signature  thomasw committed Nov 28, 2014 304 305 306  ; (poly_ids, sig_fn, nwc_tvs) <- tcExtendKindEnv2 patsyn_placeholder_kinds $-- See Note [Placeholder PatSyn kinds] tcTySigs sigs  Ian Lynagh committed May 18, 2008 307   Simon Peyton Jones committed Mar 02, 2012 308  ; let prag_fn = mkPragFun sigs (foldr (unionBags . snd) emptyBag binds)  Ian Lynagh committed May 18, 2008 309   cactus committed Nov 20, 2014 310  -- Extend the envt right away with all  Ian Lynagh committed May 18, 2008 311  -- the Ids declared with type signatures  thomasw committed Nov 28, 2014 312 313  -- Use tcExtendIdEnv3 to avoid extending the TcIdBinder stack ; tcExtendIdEnv3 [(idName id, id) | id <- poly_ids] (mkVarSet nwc_tvs)$ do  cactus committed Jul 29, 2014 314 315  { (binds', (extra_binds', thing)) <- tcBindGroups top_lvl sig_fn prag_fn binds $do { thing <- thing_inside  cactus committed Jan 20, 2015 316 317 318  -- See Note [Pattern synonym builders don't yield dependencies] ; patsyn_builders <- mapM tcPatSynBuilderBind patsyns ; let extra_binds = [ (NonRecursive, builder) | builder <- patsyn_builders ]  cactus committed Jul 29, 2014 319 320  ; return (extra_binds, thing) } ; return (binds' ++ extra_binds', thing) }}  cactus committed Jun 21, 2014 321  where  cactus committed Jul 29, 2014 322 323  patsyns = [psb | (_, lbinds) <- binds, L _ (PatSynBind psb) <- bagToList lbinds]  Simon Peyton Jones committed Jun 24, 2014 324  patsyn_placeholder_kinds -- See Note [Placeholder PatSyn kinds]  cactus committed Jul 29, 2014 325  = [(name, placeholder_patsyn_tything)| PSB{ psb_id = L _ name } <- patsyns ]  Simon Peyton Jones committed Jun 24, 2014 326  placeholder_patsyn_tything  cactus committed Jul 29, 2014 327  = AGlobal$ AConLike $PatSynCon$ panic "fakePatSynCon"  simonpj committed Mar 14, 1997 328   simonpj committed Jul 19, 2005 329 ------------------------  Simon Peyton Jones committed Mar 02, 2012 330 tcBindGroups :: TopLevelFlag -> TcSigFun -> PragFun  Ian Lynagh committed May 18, 2008 331 332  -> [(RecFlag, LHsBinds Name)] -> TcM thing -> TcM ([(RecFlag, LHsBinds TcId)], thing)  simonpj committed Jul 19, 2005 333 334 -- Typecheck a whole lot of value bindings, -- one strongly-connected component at a time  335 -- Here a "strongly connected component" has the strightforward  cactus committed Nov 20, 2014 336 -- meaning of a group of bindings that mention each other,  337 -- ignoring type signatures (that part comes later)  simonpj committed Jul 19, 2005 338   simonpj@microsoft.com committed Sep 13, 2010 339 tcBindGroups _ _ _ [] thing_inside  Ian Lynagh committed May 18, 2008 340 341  = do { thing <- thing_inside ; return ([], thing) }  simonpj committed Jul 19, 2005 342   simonpj@microsoft.com committed Sep 13, 2010 343 tcBindGroups top_lvl sig_fn prag_fn (group : groups) thing_inside  Ian Lynagh committed May 18, 2008 344  = do { (group', (groups', thing))  cactus committed Nov 20, 2014 345  <- tc_group top_lvl sig_fn prag_fn group $ simonpj@microsoft.com committed Sep 13, 2010 346  tcBindGroups top_lvl sig_fn prag_fn groups thing_inside  Ian Lynagh committed May 18, 2008 347  ; return (group' ++ groups', thing) }  sof committed May 18, 1997 348   simonpj committed Jul 19, 2005 349 ------------------------  cactus committed Nov 20, 2014 350 tc_group :: forall thing.  Simon Peyton Jones committed Mar 02, 2012 351  TopLevelFlag -> TcSigFun -> PragFun  Ian Lynagh committed May 18, 2008 352 353  -> (RecFlag, LHsBinds Name) -> TcM thing -> TcM ([(RecFlag, LHsBinds TcId)], thing)  simonpj committed Jul 19, 2005 354 355  -- Typecheck one strongly-connected component of the original program.  cactus committed Nov 20, 2014 356 -- We get a list of groups back, because there may  simonpj committed Jul 19, 2005 357 358 -- be specialisations etc as well  simonpj@microsoft.com committed Sep 13, 2010 359 tc_group top_lvl sig_fn prag_fn (NonRecursive, binds) thing_inside  Ian Lynagh committed May 18, 2008 360 361  -- A single non-recursive binding -- We want to keep non-recursive things non-recursive  simonpj committed Jul 19, 2005 362  -- so that we desugar unlifted bindings correctly  cactus committed Jan 20, 2014 363 364  = do { let bind = case bagToList binds of [bind] -> bind  cactus committed Jan 09, 2015 365 366  [] -> panic "tc_group: empty list of binds" _ -> panic "tc_group: NonRecursive binds is not a singleton bag"  cactus committed Jan 20, 2014 367 368  ; (bind', thing) <- tc_single top_lvl sig_fn prag_fn bind thing_inside ; return ( [(NonRecursive, bind')], thing) }  simonpj@microsoft.com committed Sep 13, 2010 369 370  tc_group top_lvl sig_fn prag_fn (Recursive, binds) thing_inside  cactus committed Nov 20, 2014 371 372  = -- To maximise polymorphism, we do a new -- strongly-connected-component analysis, this time omitting  Ian Lynagh committed May 18, 2008 373  -- any references to variables with type signatures.  374  -- (This used to be optional, but isn't now.)  simonpj@microsoft.com committed Sep 13, 2010 375  do { traceTc "tc_group rec" (pprLHsBinds binds)  cactus committed Jan 20, 2014 376  ; when hasPatSyn$ recursivePatSynErr binds  cactus committed Jan 09, 2015 377  ; (binds1, thing) <- go sccs  simonpj@microsoft.com committed Sep 13, 2010 378  ; return ([(Recursive, binds1)], thing) }  Ian Lynagh committed May 18, 2008 379  -- Rec them all together  simonpj committed Jul 19, 2005 380  where  cactus committed Apr 13, 2014 381  hasPatSyn = anyBag (isPatSyn . unLoc) binds  cactus committed Jan 20, 2014 382 383 384  isPatSyn PatSynBind{} = True isPatSyn _ = False  cactus committed Apr 13, 2014 385  sccs :: [SCC (LHsBind Name)]  simonpj@microsoft.com committed Sep 13, 2010 386 387  sccs = stronglyConnCompFromEdgedVertices (mkEdges sig_fn binds)  cactus committed Jan 09, 2015 388  go :: [SCC (LHsBind Name)] -> TcM (LHsBinds TcId, thing)  Simon Peyton Jones committed Aug 16, 2011 389  go (scc:sccs) = do { (binds1, ids1, closed) <- tc_scc scc  cactus committed Jan 09, 2015 390 391 392 393  ; (binds2, thing) <- tcExtendLetEnv top_lvl closed ids1 $go sccs ; return (binds1 unionBags binds2, thing) } go [] = do { thing <- thing_inside; return (emptyBag, thing) }  simonpj committed Jul 22, 2005 394   simonpj@microsoft.com committed Sep 13, 2010 395 396  tc_scc (AcyclicSCC bind) = tc_sub_group NonRecursive [bind] tc_scc (CyclicSCC binds) = tc_sub_group Recursive binds  sof committed May 18, 1997 397   simonpj@microsoft.com committed Sep 05, 2006 398  tc_sub_group = tcPolyBinds top_lvl sig_fn prag_fn Recursive  sof committed May 18, 1997 399   cactus committed Jan 20, 2014 400 401 402 403 recursivePatSynErr :: OutputableBndr name => LHsBinds name -> TcM a recursivePatSynErr binds = failWithTc$ hang (ptext (sLit "Recursive pattern synonym definition with following bindings:"))  cactus committed Apr 13, 2014 404  2 (vcat $map pprLBind . bagToList$ binds)  cactus committed Jan 20, 2014 405 406 407 408 409 410 411  where pprLoc loc = parens (ptext (sLit "defined at") <+> ppr loc) pprLBind (L loc bind) = pprWithCommas ppr (collectHsBindBinders bind) <+> pprLoc loc tc_single :: forall thing. TopLevelFlag -> TcSigFun -> PragFun  cactus committed Apr 13, 2014 412  -> LHsBind Name -> TcM thing  cactus committed Jan 20, 2014 413  -> TcM (LHsBinds TcId, thing)  cactus committed Nov 20, 2014 414 415 tc_single _top_lvl sig_fn _prag_fn (L _ (PatSynBind psb@PSB{ psb_id = L _ name })) thing_inside = do { (pat_syn, aux_binds) <- tc_pat_syn_decl  cactus committed Jan 20, 2014 416  ; let tything = AConLike (PatSynCon pat_syn)  cactus committed Jan 09, 2015 417  ; thing <- tcExtendGlobalEnv [tything] thing_inside  cactus committed Jan 20, 2014 418 419  ; return (aux_binds, thing) }  cactus committed Nov 20, 2014 420 421  where tc_pat_syn_decl = case sig_fn name of  cactus committed Jan 09, 2015 422  Nothing -> tcInferPatSynDecl psb  cactus committed Nov 20, 2014 423  Just (TcPatSynInfo tpsi) -> tcCheckPatSynDecl psb tpsi  cactus committed Jan 09, 2015 424  Just _ -> panic "tc_single"  cactus committed Nov 20, 2014 425   cactus committed Jan 20, 2014 426 427 428 429 430 431 tc_single top_lvl sig_fn prag_fn lbind thing_inside = do { (binds1, ids, closed) <- tcPolyBinds top_lvl sig_fn prag_fn NonRecursive NonRecursive [lbind] ; thing <- tcExtendLetEnv top_lvl closed ids thing_inside ; return (binds1, thing) }  cactus committed Nov 20, 2014 432   thomasw committed Nov 28, 2014 433 434 435 436 437 -- | No signature or a partial signature noCompleteSig :: Maybe TcSigInfo -> Bool noCompleteSig Nothing = True noCompleteSig (Just sig) = isPartialSig sig  simonpj committed Aug 10, 2005 438 ------------------------  cactus committed Jan 09, 2015 439 mkEdges :: TcSigFun -> LHsBinds Name -> [Node BKey (LHsBind Name)]  simonpj committed Aug 10, 2005 440   cactus committed Jan 09, 2015 441 type BKey = Int -- Just number off the bindings  simonpj committed Aug 10, 2005 442 443  mkEdges sig_fn binds  444  = [ (bind, key, [key | n <- nameSetElems (bind_fvs (unLoc bind)),  Ian Lynagh committed May 18, 2008 445  Just key <- [lookupNameEnv key_map n], no_sig n ])  simonpj committed Aug 10, 2005 446 447 448 449  | (bind, key) <- keyd_binds ] where no_sig :: Name -> Bool  thomasw committed Nov 28, 2014 450  no_sig n = noCompleteSig (sig_fn n)  simonpj committed Aug 10, 2005 451 452 453  keyd_binds = bagToList binds zip [0::BKey ..]  Ian Lynagh committed May 18, 2008 454  key_map :: NameEnv BKey -- Which binding it comes from  cactus committed Apr 13, 2014 455  key_map = mkNameEnv [(bndr, key) | (L _ bind, key) <- keyd_binds  cactus committed Jan 09, 2015 456  , bndr <- collectHsBindBinders bind ]  simonpj committed Mar 14, 1997 457   simonpj committed Jul 19, 2005 458 ------------------------  Simon Peyton Jones committed Mar 02, 2012 459 tcPolyBinds :: TopLevelFlag -> TcSigFun -> PragFun  cactus committed Jan 09, 2015 460 461 462 463  -> RecFlag -- Whether the group is really recursive -> RecFlag -- Whether it's recursive after breaking -- dependencies based on type signatures -> [LHsBind Name] -- None are PatSynBind  chak@cse.unsw.edu.au. committed Oct 31, 2011 464  -> TcM (LHsBinds TcId, [TcId], TopLevelFlag)  simonpj committed Jul 19, 2005 465   cactus committed Jan 09, 2015 466 -- Typechecks a single bunch of values bindings all together,  simonpj committed Jul 19, 2005 467 468 469 -- and generalises them. The bunch may be only part of a recursive -- group, because we use type signatures to maximise polymorphism --  simonpj committed Jul 22, 2005 470 471 -- Returns a list because the input may be a single non-recursive binding, -- in which case the dependency order of the resulting bindings is  cactus committed Nov 20, 2014 472 473 -- important. --  simonpj committed Jul 19, 2005 474 -- Knows nothing about the scope of the bindings  cactus committed Jan 09, 2015 475 -- None of the bindings are pattern synonyms  simonpj committed Jul 19, 2005 476   simonpj@microsoft.com committed Sep 13, 2010 477 478 tcPolyBinds top_lvl sig_fn prag_fn rec_group rec_tc bind_list = setSrcSpan loc $ cactus committed Nov 20, 2014 479  recoverM (recoveryCode binder_names sig_fn)$ do  simonpj@microsoft.com committed Mar 31, 2011 480  -- Set up main recover; take advantage of any type sigs  simonpj committed Sep 30, 2004 481   Austin Seipp committed Sep 09, 2014 482  { traceTc "------------------------------------------------" Outputable.empty  Simon Peyton Jones committed May 09, 2012 483  ; traceTc "Bindings for {" (ppr binder_names)  Ian Lynagh committed Jan 19, 2012 484  ; dflags <- getDynFlags  Simon Peyton Jones committed Aug 16, 2011 485  ; type_env <- getLclTypeEnv  cactus committed Nov 20, 2014 486  ; let plan = decideGeneralisationPlan dflags type_env  Simon Peyton Jones committed Mar 02, 2012 487  binder_names bind_list sig_fn  simonpj@microsoft.com committed Sep 13, 2010 488  ; traceTc "Generalisation plan" (ppr plan)  Simon Peyton Jones committed May 09, 2012 489  ; result@(tc_binds, poly_ids, _) <- case plan of  cactus committed Jan 20, 2014 490 491 492  NoGen -> tcPolyNoGen rec_tc prag_fn sig_fn bind_list InferGen mn cl -> tcPolyInfer rec_tc prag_fn sig_fn mn cl bind_list CheckGen lbind sig -> tcPolyCheck rec_tc prag_fn sig lbind  simonpj@microsoft.com committed Sep 13, 2010 493   chak@cse.unsw.edu.au. committed Oct 31, 2011 494  -- Check whether strict bindings are ok  Ian Lynagh committed May 18, 2008 495 496  -- These must be non-recursive etc, and are not generalised -- They desugar to a case expression in the end  Simon Peyton Jones committed May 09, 2012 497 498 499 500  ; checkStrictBinds top_lvl rec_group bind_list tc_binds poly_ids ; traceTc "} End of bindings for" (vcat [ ppr binder_names, ppr rec_group , vcat [ppr id <+> ppr (idType id) | id <- poly_ids] ])  simonpj@microsoft.com committed Sep 13, 2010 501   Simon Peyton Jones committed Aug 16, 2011 502  ; return result }  simonpj@microsoft.com committed Sep 13, 2010 503  where  cactus committed Apr 13, 2014 504 505  binder_names = collectHsBindListBinders bind_list loc = foldr1 combineSrcSpans (map getLoc bind_list)  cactus committed Nov 20, 2014 506  -- The mbinds have been dependency analysed and  simonpj@microsoft.com committed Mar 31, 2011 507  -- may no longer be adjacent; so find the narrowest  chak@cse.unsw.edu.au. committed Oct 31, 2011 508  -- span that includes them all  simonpj@microsoft.com committed Sep 13, 2010 509   510 ------------------  Simon Peyton Jones committed Sep 17, 2012 511 tcPolyNoGen -- No generalisation whatsoever  Simon Peyton Jones committed Sep 10, 2013 512  :: RecFlag -- Whether it's recursive after breaking  simonpj@microsoft.com committed Sep 13, 2010 513  -- dependencies based on type signatures  Simon Peyton Jones committed Sep 17, 2012 514  -> PragFun -> TcSigFun  cactus committed Apr 13, 2014 515  -> [LHsBind Name]  Simon Peyton Jones committed Aug 16, 2011 516  -> TcM (LHsBinds TcId, [TcId], TopLevelFlag)  simonpj@microsoft.com committed Sep 13, 2010 517   Simon Peyton Jones committed Sep 10, 2013 518 519 tcPolyNoGen rec_tc prag_fn tc_sig_fn bind_list = do { (binds', mono_infos) <- tcMonoBinds rec_tc tc_sig_fn  cactus committed Nov 20, 2014 520  (LetGblBndr prag_fn)  Simon Peyton Jones committed Sep 17, 2012 521  bind_list  simonpj@microsoft.com committed Sep 13, 2010 522  ; mono_ids' <- mapM tc_mono_info mono_infos  Simon Peyton Jones committed Aug 16, 2011 523  ; return (binds', mono_ids', NotTopLevel) }  simonpj@microsoft.com committed Sep 13, 2010 524 525  where tc_mono_info (name, _, mono_id)  Simon Peyton Jones committed Feb 16, 2012 526  = do { mono_ty' <- zonkTcType (idType mono_id)  chak@cse.unsw.edu.au. committed Oct 31, 2011 527  -- Zonk, mainly to expose unboxed types to checkStrictBinds  simonpj@microsoft.com committed Sep 13, 2010 528  ; let mono_id' = setIdType mono_id mono_ty'  simonpj@microsoft.com committed Oct 07, 2010 529  ; _specs <- tcSpecPrags mono_id' (prag_fn name)  530  ; return mono_id' }  chak@cse.unsw.edu.au. committed Oct 31, 2011 531 532 533 534  -- NB: tcPrags generates error messages for -- specialisation pragmas for non-overloaded sigs -- Indeed that is why we call it here! -- So we can safely ignore _specs  simonpj@microsoft.com committed Sep 13, 2010 535 536  ------------------  Simon Peyton Jones committed Sep 10, 2013 537 tcPolyCheck :: RecFlag -- Whether it's recursive after breaking  chak@cse.unsw.edu.au. committed Oct 31, 2011 538  -- dependencies based on type signatures  Simon Peyton Jones committed Jan 06, 2015 539 540  -> PragFun -> TcSigInfo  cactus committed Apr 13, 2014 541  -> LHsBind Name  chak@cse.unsw.edu.au. committed Oct 31, 2011 542  -> TcM (LHsBinds TcId, [TcId], TopLevelFlag)  cactus committed Nov 20, 2014 543 -- There is just one binding,  simonpj@microsoft.com committed Sep 13, 2010 544 545 -- it binds a single variable, -- it has a signature,  Simon Peyton Jones committed Sep 10, 2013 546 tcPolyCheck rec_tc prag_fn  thomasw committed Feb 18, 2015 547 548  sig@(TcSigInfo { sig_name = name, sig_poly_id = Just poly_id , sig_tvs = tvs_w_scoped  thomasw committed Nov 28, 2014 549  , sig_nwcs = sig_nwcs, sig_theta = theta  Simon Peyton Jones committed Jan 06, 2015 550 551  , sig_tau = tau, sig_loc = loc , sig_warn_redundant = warn_redundant })  cactus committed Apr 13, 2014 552  bind  thomasw committed Nov 28, 2014 553 554  = ASSERT( null sig_nwcs ) -- We should be in tcPolyInfer if there are wildcards do { ev_vars <- newEvVars theta  thomasw committed Feb 18, 2015 555  ; let ctxt = FunSigCtxt name warn_redundant  Simon Peyton Jones committed Jan 06, 2015 556  skol_info = SigSkol ctxt (mkPhiTy theta tau)  thomasw committed Feb 18, 2015 557  prag_sigs = prag_fn name  Simon Peyton Jones committed Mar 07, 2014 558  tvs = map snd tvs_w_scoped  cactus committed Nov 20, 2014 559 560  ; (ev_binds, (binds', [mono_info])) <- setSrcSpan loc $ Simon Peyton Jones committed Mar 02, 2012 561  checkConstraints skol_info tvs ev_vars$  cactus committed Jan 20, 2014 562  tcMonoBinds rec_tc (\_ -> Just sig) LetLclBndr [bind]  simonpj@microsoft.com committed Sep 13, 2010 563   Simon Peyton Jones committed Aug 16, 2011 564 565  ; spec_prags <- tcSpecPrags poly_id prag_sigs ; poly_id <- addInlinePrags poly_id prag_sigs  simonpj@microsoft.com committed Sep 13, 2010 566   Simon Peyton Jones committed Aug 16, 2011 567 568 569 570 571  ; let (_, _, mono_id) = mono_info export = ABE { abe_wrap = idHsWrapper , abe_poly = poly_id , abe_mono = mono_id , abe_prags = SpecPrags spec_prags }  cactus committed Nov 20, 2014 572  abs_bind = L loc $AbsBinds  simonpj@microsoft.com committed Sep 13, 2010 573  { abs_tvs = tvs  Simon Peyton Jones committed Jan 06, 2015 574  , abs_ev_vars = ev_vars, abs_ev_binds = [ev_binds]  simonpj@microsoft.com committed Sep 13, 2010 575  , abs_exports = [export], abs_binds = binds' }  Simon Peyton Jones committed Aug 16, 2011 576 577  closed | isEmptyVarSet (tyVarsOfType (idType poly_id)) = TopLevel | otherwise = NotTopLevel  cactus committed Apr 13, 2014 578  ; return (unitBag abs_bind, [poly_id], closed) }  simonpj@microsoft.com committed Sep 13, 2010 579   cactus committed Nov 20, 2014 580 581 582 tcPolyCheck _rec_tc _prag_fn sig _bind = pprPanic "tcPolyCheck" (ppr sig)  583 ------------------  cactus committed Nov 20, 2014 584 tcPolyInfer  Simon Peyton Jones committed Sep 10, 2013 585  :: RecFlag -- Whether it's recursive after breaking  simonpj@microsoft.com committed Sep 13, 2010 586  -- dependencies based on type signatures  cactus committed Nov 20, 2014 587  -> PragFun -> TcSigFun  Simon Peyton Jones committed Sep 17, 2012 588 589  -> Bool -- True <=> apply the monomorphism restriction -> Bool -- True <=> free vars have closed types  cactus committed Apr 13, 2014 590  -> [LHsBind Name]  Simon Peyton Jones committed Aug 16, 2011 591  -> TcM (LHsBinds TcId, [TcId], TopLevelFlag)  Simon Peyton Jones committed Sep 10, 2013 592 tcPolyInfer rec_tc prag_fn tc_sig_fn mono closed bind_list  Simon Peyton Jones committed Jan 06, 2015 593 594  = do { ((binds', mono_infos), tclvl, wanted) <- pushLevelAndCaptureConstraints$  Simon Peyton Jones committed Sep 10, 2013 595  tcMonoBinds rec_tc tc_sig_fn LetLclBndr bind_list  simonpj@microsoft.com committed Sep 13, 2010 596   simonpj@microsoft.com committed Jan 12, 2011 597  ; let name_taus = [(name, idType mono_id) | (name, _, mono_id) <- mono_infos]  Simon Peyton Jones committed May 22, 2013 598  ; traceTc "simplifyInfer call" (ppr name_taus $$ppr wanted)  Simon Peyton Jones committed Jun 11, 2014 599  ; (qtvs, givens, mr_bites, ev_binds)  Simon Peyton Jones committed Dec 02, 2014 600  <- simplifyInfer tclvl mono name_taus wanted  simonpj@microsoft.com committed Sep 13, 2010 601   Simon Peyton Jones committed Feb 13, 2015 602  ; let inferred_theta = map evVarPred givens  thomasw committed Nov 28, 2014 603 604 605  ; exports <- checkNoErrs  mapM (mkExport prag_fn qtvs inferred_theta) mono_infos  simonpj@microsoft.com committed Sep 13, 2010 606  ; loc <- getSrcSpanM  Simon Peyton Jones committed Aug 16, 2011 607  ; let poly_ids = map abe_poly exports  chak@cse.unsw.edu.au. committed Oct 31, 2011 608 609  final_closed | closed && not mr_bites = TopLevel | otherwise = NotTopLevel  cactus committed Nov 20, 2014 610  abs_bind = L loc   Simon Peyton Jones committed Aug 16, 2011 611  AbsBinds { abs_tvs = qtvs  Simon Peyton Jones committed Jan 06, 2015 612  , abs_ev_vars = givens, abs_ev_binds = [ev_binds]  Simon Peyton Jones committed Aug 16, 2011 613  , abs_exports = exports, abs_binds = binds' }  simonpj@microsoft.com committed Sep 13, 2010 614   Simon Peyton Jones committed Sep 01, 2011 615 616  ; traceTc "Binding:" (ppr final_closed$$ ppr (poly_ids zip map idType poly_ids))  cactus committed Apr 13, 2014 617  ; return (unitBag abs_bind, poly_ids, final_closed) }  Simon Peyton Jones committed Aug 16, 2011 618  -- poly_ids are guaranteed zonked by mkExport  simonpj committed Jul 19, 2005 619 620  --------------  Simon Peyton Jones committed Oct 03, 2013 621 mkExport :: PragFun  chak@cse.unsw.edu.au. committed Oct 31, 2011 622  -> [TyVar] -> TcThetaType -- Both already zonked  Ian Lynagh committed May 18, 2008 623  -> MonoBindInfo  Simon Peyton Jones committed Aug 16, 2011 624  -> TcM (ABExport Id)  Simon Peyton Jones committed Oct 03, 2013 625 626 627 628 -- Only called for generalisation plan IferGen, not by CheckGen or NoGen -- -- mkExport generates exports with -- zonked type variables,  Ian Lynagh committed May 18, 2008 629 -- zonked poly_ids  simonpj@microsoft.com committed Sep 18, 2006 630 631 632 633 -- The former is just because no further unifications will change -- the quantified type variables, so we can fix their final form -- right now. -- The latter is needed because the poly_ids are used to extend the  Simon Peyton Jones committed Oct 03, 2013 634 -- type environment; see the invariant on TcEnv.tcExtendIdEnv  simonpj@microsoft.com committed Sep 18, 2006 635   Simon Peyton Jones committed Aug 16, 2011 636 -- Pre-condition: the qtvs and theta are already zonked  simonpj@microsoft.com committed Sep 18, 2006 637   thomasw committed Nov 28, 2014 638 mkExport prag_fn qtvs inferred_theta (poly_name, mb_sig, mono_id)  Simon Peyton Jones committed Feb 16, 2012 639  = do { mono_ty <- zonkTcType (idType mono_id)  640   Simon Peyton Jones committed Jun 11, 2014 641  ; poly_id <- case mb_sig of  thomasw committed Nov 28, 2014 642 643  Nothing -> mkInferredPolyId poly_name qtvs inferred_theta mono_ty Just (TcPatSynInfo _) -> panic "mkExport"  thomasw committed Feb 18, 2015 644 645 646  Just sig | Just id <- sig_poly_id sig -> return id Just sig -> do { final_theta <- completeTheta inferred_theta sig  thomasw committed Nov 28, 2014 647  ; mkInferredPolyId poly_name qtvs final_theta mono_ty }  Simon Peyton Jones committed Jun 11, 2014 648 649  -- NB: poly_id has a zonked type  Simon Peyton Jones committed Aug 16, 2011 650  ; poly_id <- addInlinePrags poly_id prag_sigs  simonpj@microsoft.com committed Oct 07, 2010 651  ; spec_prags <- tcSpecPrags poly_id prag_sigs  Ian Lynagh committed May 18, 2008 652  -- tcPrags requires a zonked poly_id  simonpj@microsoft.com committed Sep 18, 2006 653   thomasw committed Nov 28, 2014 654  ; let sel_poly_ty = mkSigmaTy qtvs inferred_theta mono_ty  Simon Peyton Jones committed Oct 03, 2013 655  ; traceTc "mkExport: check sig"  thomasw committed Nov 28, 2014 656  (vcat [ ppr poly_name, ppr sel_poly_ty, ppr (idType poly_id) ])  Simon Peyton Jones committed Aug 16, 2011 657   chak@cse.unsw.edu.au. committed Oct 31, 2011 658 659 660  -- Perform the impedence-matching and ambiguity check -- right away. If it fails, we want to fail now (and recover -- in tcPolyBinds). If we delay checking, we get an error cascade.  Simon Peyton Jones committed Oct 03, 2013 661  -- Remember we are in the tcPolyInfer case, so the type envt is  chak@cse.unsw.edu.au. committed Oct 31, 2011 662 663  -- closed (unless we are doing NoMonoLocalBinds in which case all bets -- are off)  664  -- See Note [Impedence matching]  Simon Peyton Jones committed Jun 11, 2014 665  ; (wrap, wanted) <- addErrCtxtM (mk_bind_msg inferred True poly_name (idType poly_id)) $ Simon Peyton Jones committed Aug 16, 2011 666  captureConstraints$  Simon Peyton Jones committed Nov 21, 2014 667  tcSubType_NC sig_ctxt sel_poly_ty (idType poly_id)  Simon Peyton Jones committed Oct 03, 2013 668  ; ev_binds <- simplifyTop wanted  Simon Peyton Jones committed Aug 16, 2011 669 670 671 672 673  ; return (ABE { abe_wrap = mkWpLet (EvBinds ev_binds) <.> wrap , abe_poly = poly_id , abe_mono = mono_id , abe_prags = SpecPrags spec_prags }) }  simonpj@microsoft.com committed Sep 18, 2006 674  where  Simon Peyton Jones committed Aug 16, 2011 675 676 677  inferred = isNothing mb_sig prag_sigs = prag_fn poly_name sig_ctxt = InfSigCtxt poly_name  Simon Peyton Jones committed Jun 11, 2014 678 679 680 681 682 683  mkInferredPolyId :: Name -> [TyVar] -> TcThetaType -> TcType -> TcM Id -- In the inference case (no signature) this stuff figures out -- the right type variables and theta to quantify over -- See Note [Validity of inferred types] mkInferredPolyId poly_name qtvs theta mono_ty  Simon Peyton Jones committed Nov 04, 2014 684 685 686  = do { fam_envs <- tcGetFamInstEnvs ; let (_co, norm_mono_ty) = normaliseType fam_envs Nominal mono_ty  Simon Peyton Jones committed Nov 06, 2014 687 688  -- Unification may not have normalised the type, -- (see Note [Lazy flattening] in TcFlatten) so do it  Simon Peyton Jones committed Nov 04, 2014 689 690 691  -- here to make it as uncomplicated as possible. -- Example: f :: [F Int] -> Bool -- should be rewritten to f :: [Char] -> Bool, if possible  Simon Peyton Jones committed Nov 06, 2014 692   Simon Peyton Jones committed Nov 04, 2014 693  my_tvs2 = closeOverKinds (growThetaTyVars theta (tyVarsOfType norm_mono_ty))  Simon Peyton Jones committed Jun 11, 2014 694  -- Include kind variables! Trac #7916  Simon Peyton Jones committed Nov 06, 2014 695   Simon Peyton Jones committed Nov 04, 2014 696 697 698 699 700 701  my_tvs = filter (elemVarSet my_tvs2) qtvs -- Maintain original order my_theta = filter (quantifyPred my_tvs2) theta inferred_poly_ty = mkSigmaTy my_tvs my_theta norm_mono_ty ; addErrCtxtM (mk_bind_msg True False poly_name inferred_poly_ty) $checkValidType (InfSigCtxt poly_name) inferred_poly_ty  Simon Peyton Jones committed Nov 21, 2014 702   Simon Peyton Jones committed Nov 04, 2014 703  ; return (mkLocalId poly_name inferred_poly_ty) }  Simon Peyton Jones committed Jun 11, 2014 704 705 706  mk_bind_msg :: Bool -> Bool -> Name -> TcType -> TidyEnv -> TcM (TidyEnv, SDoc) mk_bind_msg inferred want_ambig poly_name poly_ty tidy_env  Simon Peyton Jones committed Nov 21, 2014 707 708  = do { (tidy_env', tidy_ty) <- zonkTidyTcType tidy_env poly_ty ; return (tidy_env', mk_msg tidy_ty) }  Simon Peyton Jones committed Jun 11, 2014 709  where  Simon Peyton Jones committed Nov 21, 2014 710 711 712 713 714  mk_msg ty = vcat [ ptext (sLit "When checking that") <+> quotes (ppr poly_name) <+> ptext (sLit "has the") <+> what <+> ptext (sLit "type") , nest 2 (ppr poly_name <+> dcolon <+> ppr ty) , ppWhen want_ambig$ ptext (sLit "Probable cause: the inferred type is ambiguous") ]  Simon Peyton Jones committed Jun 11, 2014 715 716  what | inferred = ptext (sLit "inferred") | otherwise = ptext (sLit "specified")  thomasw committed Nov 28, 2014 717 718 719 720 721 722 723 724 725 726  -- | Report the inferred constraints for an extra-constraints wildcard/hole as -- an error message, unless the PartialTypeSignatures flag is enabled. In this -- case, the extra inferred constraints are accepted without complaining. -- Returns the annotated constraints combined with the inferred constraints. completeTheta :: TcThetaType -> TcSigInfo -> TcM TcThetaType completeTheta _ (TcPatSynInfo _) = panic "Extra-constraints wildcard not supported in a pattern signature" completeTheta inferred_theta  thomasw committed Feb 18, 2015 727  sig@(TcSigInfo { sig_extra_cts = mb_extra_cts  thomasw committed Nov 28, 2014 728 729 730 731 732 733 734 735 736  , sig_theta = annotated_theta }) | Just loc <- mb_extra_cts = do { annotated_theta <- zonkTcThetaType annotated_theta ; let inferred_diff = minusList inferred_theta annotated_theta final_theta = annotated_theta ++ inferred_diff ; partial_sigs <- xoptM Opt_PartialTypeSignatures ; warn_partial_sigs <- woptM Opt_WarnPartialTypeSignatures ; msg <- mkLongErrAt loc (mk_msg inferred_diff partial_sigs) empty ; case partial_sigs of  Simon Peyton Jones committed Jan 09, 2015 737  True | warn_partial_sigs -> reportWarning msg  thomasw committed Nov 28, 2014 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753  | otherwise -> return () False -> reportError msg ; return final_theta } | otherwise = zonkTcThetaType annotated_theta -- No extra-constraints wildcard means no extra constraints will be added -- to the context, so just return the possibly empty (zonked) -- annotated_theta. where pts_hint = text "To use the inferred type, enable PartialTypeSignatures" mk_msg inferred_diff suppress_hint = vcat [ hang ((text "Found hole") <+> quotes (char '_')) 2 (text "with inferred constraints:") <+> pprTheta inferred_diff , if suppress_hint then empty else pts_hint  thomasw committed Feb 18, 2015 754  , typeSigCtxt sig ]  simonpj committed Jul 19, 2005 755   Austin Seipp committed Dec 03, 2014 756 {-  Simon Peyton Jones committed Jan 06, 2015 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 Note [Partial type signatures and generalisation] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When we have a partial type signature, like f :: _ -> Int then we *always* use the InferGen plan, and hence tcPolyInfer. We do this even for a local binding with -XMonoLocalBinds. Reasons: * The TcSigInfo for 'f' has a unification variable for the '_', whose TcLevel is one level deeper than the current level. (See pushTcLevelM in tcTySig.) But NoGen doesn't increase the TcLevel like InferGen, so we lose the level invariant. * The signature might be f :: forall a. _ -> a so it really is polymorphic. It's not clear what it would mean to use NoGen on this, and indeed the ASSERT in tcLhs, in the (Just sig) case, checks that if there is a signature then we are using LetLclBndr, and hence a nested AbsBinds with increased TcLevel It might be possible to fix these difficulties somehow, but there doesn't seem much point. Indeed, adding a partial type signature is a way to get per-binding inferred generalisation.  Simon Peyton Jones committed Jun 11, 2014 780 781 Note [Validity of inferred types] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  cactus committed Nov 20, 2014 782 We need to check inferred type for validity, in case it uses language  Simon Peyton Jones committed Jun 11, 2014 783 784 785 786 787 788 789 790 791 792 extensions that are not turned on. The principle is that if the user simply adds the inferred type to the program source, it'll compile fine. See #8883. Examples that might fail: - an inferred theta that requires type equalities e.g. (F a ~ G b) or multi-parameter type classes - an inferred type that includes unboxed tuples However we don't do the ambiguity check (checkValidType omits it for  cactus committed Nov 20, 2014 793 InfSigCtxt) because the impedence-matching stage, which follows  Simon Peyton Jones committed Jun 11, 2014 794 795 796 797 798 immediately, will do it and we don't want two error messages. Moreover, because of the impedence matching stage, the ambiguity-check suggestion of -XAllowAmbiguiousTypes will not work.  799 800 801 802 803 804 805 806 807 808 Note [Impedence matching] ~~~~~~~~~~~~~~~~~~~~~~~~~ Consider f 0 x = x f n x = g [] (not x) g [] y = f 10 y g _ y = f 9 y After typechecking we'll get  cactus committed Nov 20, 2014 809 810  f_mono_ty :: a -> Bool -> Bool g_mono_ty :: [b] -> Bool -> Bool  811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 with constraints (Eq a, Num a) Note that f is polymorphic in 'a' and g in 'b'; and these are not linked. The types we really want for f and g are f :: forall a. (Eq a, Num a) => a -> Bool -> Bool g :: forall b. [b] -> Bool -> Bool We can get these by "impedence matching": tuple :: forall a b. (Eq a, Num a) => (a -> Bool -> Bool, [b] -> Bool -> Bool) tuple a b d1 d1 = let ...bind f_mono, g_mono in (f_mono, g_mono) f a d1 d2 = case tuple a Any d1 d2 of (f, g) -> f g b = case tuple Integer b dEqInteger dNumInteger of (f,g) -> g Suppose the shared quantified tyvars are qtvs and constraints theta.  cactus committed Nov 20, 2014 827 Then we want to check that  828  f's polytype is more polymorphic than forall qtvs. theta => f_mono_ty  cactus committed Nov 20, 2014 829 and the proof is the impedence matcher.  830 831 832 833 834 835  Notice that the impedence matcher may do defaulting. See Trac #7173. It also cleverly does an ambiguity check; for example, rejecting f :: F a -> a where F is a non-injective type function.  Austin Seipp committed Dec 03, 2014 836 -}  837   Simon Peyton Jones committed Jan 14, 2015 838 839 840 841 842 843 844 -------------- -- If typechecking the binds fails, then return with each -- signature-less binder given type (forall a.a), to minimise -- subsequent error messages recoveryCode :: [Name] -> TcSigFun -> TcM (LHsBinds TcId, [Id], TopLevelFlag) recoveryCode binder_names sig_fn = do { traceTc "tcBindsWithSigs: error recovery" (ppr binder_names)  thomasw committed Feb 18, 2015 845  ; let poly_ids = map mk_dummy binder_names  Simon Peyton Jones committed Jan 14, 2015 846 847 848 849  ; return (emptyBag, poly_ids, if all is_closed poly_ids then TopLevel else NotTopLevel) } where mk_dummy name  thomasw committed Feb 18, 2015 850 851 852 853  | Just (TcSigInfo { sig_poly_id = Just poly_id }) <- sig_fn name = poly_id | otherwise = mkLocalId name forall_a_a  Simon Peyton Jones committed Jan 14, 2015 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968  is_closed poly_id = isEmptyVarSet (tyVarsOfType (idType poly_id)) forall_a_a :: TcType forall_a_a = mkForAllTy openAlphaTyVar (mkTyVarTy openAlphaTyVar) {- ********************************************************************* * * Pragmas, including SPECIALISE * * ************************************************************************ Note [Handling SPECIALISE pragmas] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The basic idea is this: f:: Num a => a -> b -> a {-# SPECIALISE foo :: Int -> b -> Int #-} We check that (forall a. Num a => a -> a) is more polymorphic than Int -> Int (for which we could use tcSubType, but see below), generating a HsWrapper to connect the two, something like wrap = /\b. Int b dNumInt This wrapper is put in the TcSpecPrag, in the ABExport record of the AbsBinds. f :: (Eq a, Ix b) => a -> b -> Bool {-# SPECIALISE f :: (Ix p, Ix q) => Int -> (p,q) -> Bool #-} f = From this the typechecker generates AbsBinds [ab] [d1,d2] [([ab], f, f_mono, prags)] binds SpecPrag (wrap_fn :: forall a b. (Eq a, Ix b) => XXX -> forall p q. (Ix p, Ix q) => XXX[ Int/a, (p,q)/b ]) From these we generate: Rule: forall p, q, (dp:Ix p), (dq:Ix q). f Int (p,q) dInt ($dfInPair dp dq) = f_spec p q dp dq Spec bind: f_spec = wrap_fn Note that * The LHS of the rule may mention dictionary *expressions* (eg$dfIxPair dp dq), and that is essential because the dp, dq are needed on the RHS. * The RHS of f_spec, has a *copy* of 'binds', so that it can fully specialise it. From the TcSpecPrag, in DsBinds we generate a binding for f_spec and a RULE: f_spec :: Int -> b -> Int f_spec = wrap RULE: forall b (d:Num b). f b d = f_spec b The RULE is generated by taking apart the HsWrapper, which is a little delicate, but works. Some wrinkles 1. We don't use full-on tcSubType, because that does co and contra variance and that in turn will generate too complex a LHS for the RULE. So we use a single invocation of deeplySkolemise / deeplyInstantiate in tcSpecWrapper. (Actually I think that even the "deeply" stuff may be too much, because it introduces lambdas, though I think it can be made to work without too much trouble.) 2. We need to take care with type families (Trac #5821). Consider type instance F Int = Bool f :: Num a => a -> F a {-# SPECIALISE foo :: Int -> Bool #-} We *could* try to generate an f_spec with precisely the declared type: f_spec :: Int -> Bool f_spec = Int dNumInt |> co RULE: forall d. f Int d = f_spec |> sym co but the 'co' and 'sym co' are (a) playing no useful role, and (b) are hard to generate. At all costs we must avoid this: RULE: forall d. f Int d |> co = f_spec because the LHS will never match (indeed it's rejected in decomposeRuleLhs). So we simply do this: - Generate a constraint to check that the specialised type (after skolemiseation) is equal to the instantiated function type. - But *discard* the evidence (coercion) for that constraint, so that we ultimately generate the simpler code f_spec :: Int -> F Int f_spec = Int dNumInt RULE: forall d. f Int d = f_spec You can see this discarding happening in 3. Note that the HsWrapper can transform *any* function with the right type prefix forall ab. (Eq a, Ix b) => XXX regardless of XXX. It's sort of polymorphic in XXX. This is useful: we use the same wrapper to transform each of the class ops, as well as the dict. That's what goes on in TcInstDcls.mk_meth_spec_prags -}  simonpj@microsoft.com committed Sep 13, 2010 969 type PragFun = Name -> [LSig Name]  simonpj committed Jul 19, 2005 970   simonpj@microsoft.com committed Sep 13, 2010 971 mkPragFun :: [LSig Name] -> LHsBinds Name -> PragFun  simonpj@microsoft.com committed Jan 06, 2010 972 973 mkPragFun sigs binds = \n -> lookupNameEnv prag_env n orElse [] where  Icelandjack committed Feb 13, 2014 974  prs = mapMaybe get_sig sigs  simonpj@microsoft.com committed Jan 06, 2010 975 976 977 978 979 980 981  get_sig :: LSig Name -> Maybe (Located Name, LSig Name) get_sig (L l (SpecSig nm ty inl)) = Just (nm, L l $SpecSig nm ty (add_arity nm inl)) get_sig (L l (InlineSig nm inl)) = Just (nm, L l$ InlineSig nm (add_arity nm inl)) get_sig _ = Nothing add_arity (L _ n) inl_prag -- Adjust inl_sat field to match visible arity of function  Simon Marlow committed Oct 15, 2010 982 983 984  | Just ar <- lookupNameEnv ar_env n, Inline <- inl_inline inl_prag = inl_prag { inl_sat = Just ar } -- add arity only for real INLINE pragmas, not INLINABLE  simonpj@microsoft.com committed Jan 06, 2010 985 986 987 988 989 990 991 992  | otherwise = inl_prag prag_env :: NameEnv [LSig Name] prag_env = foldl add emptyNameEnv prs add env (L _ n,p) = extendNameEnv_Acc (:) singleton env n p -- ar_env maps a local to the arity of its definition ar_env :: NameEnv Arity  cactus committed Apr 13, 2014 993  ar_env = foldrBag lhsBindArity emptyNameEnv binds  simonpj@microsoft.com committed Jan 06, 2010 994 995 996 997  lhsBindArity :: LHsBind Name -> NameEnv Arity -> NameEnv Arity lhsBindArity (L _ (FunBind { fun_id = id, fun_matches = ms })) env = extendNameEnv env (unLoc id) (matchGroupArity ms)  chak@cse.unsw.edu.au. committed Oct 31, 2011 998 lhsBindArity _ env = env -- PatBind/VarBind  simonpj committed Jul 19, 2005 999   1000 ------------------  simonpj@microsoft.com committed Oct 07, 2010 1001 1002 tcSpecPrags :: Id -> [LSig Name] -> TcM [LTcSpecPrag]  simonpj@microsoft.com committed Jul 21, 2010 1003 -- Add INLINE and SPECIALSE pragmas  simonpj@microsoft.com committed Jan 06, 2010 1004 1005 -- INLINE prags are added to the (polymorphic) Id directly -- SPECIALISE prags are passed to the desugarer via TcSpecPrags  Simon Marlow committed Dec 16, 2008 1006 1007 -- Pre-condition: the poly_id is zonked -- Reason: required by tcSubExp  simonpj@microsoft.com committed Oct 07, 2010 1008 tcSpecPrags poly_id prag_sigs  Simon Peyton Jones committed Mar 13, 2014 1009 1010  = do { traceTc "tcSpecPrags" (ppr poly_id <+> ppr spec_sigs) ; unless (null bad_sigs) warn_discarded_sigs  Simon Peyton Jones committed Jan 14, 2015 1011  ; pss <- mapAndRecoverM (wrapLocM (tcSpecPrag poly_id)) spec_sigs  Alan Zimmerman committed Nov 21, 2014 1012  ; return $concatMap (\(L l ps) -> map (L l) ps) pss }  simonpj@microsoft.com committed Oct 29, 2009 1013  where  1014 1015 1016 1017  spec_sigs = filter isSpecLSig prag_sigs bad_sigs = filter is_bad_sig prag_sigs is_bad_sig s = not (isSpecLSig s || isInlineLSig s)  simonpj@microsoft.com committed Oct 07, 2010 1018 1019 1020 1021 1022  warn_discarded_sigs = warnPrags poly_id bad_sigs$ ptext (sLit "Discarding unexpected pragmas for") --------------  Simon Peyton Jones committed Jan 14, 2015 1023 1024 1025 1026 1027 1028 1029 1030 1031 tcSpecPrag :: TcId -> Sig Name -> TcM [TcSpecPrag] tcSpecPrag poly_id prag@(SpecSig fun_name hs_tys inl) -- See Note [Handling SPECIALISE pragmas] -- -- The Name fun_name in the SpecSig may not be the same as that of the poly_id -- Example: SPECIALISE for a class method: the Name in the SpecSig is -- for the selector Id, but the poly_id is something like $cop -- However we want to use fun_name in the error message, since that is -- what the user wrote (Trac #8537)  simonpj@microsoft.com committed Oct 07, 2010 1032  = addErrCtxt (spec_ctxt prag)$  Alan Zimmerman committed Nov 21, 2014 1033  do { spec_tys <- mapM (tcHsSigType sig_ctxt) hs_tys  simonpj@microsoft.com committed Oct 27, 2010 1034  ; warnIf (not (isOverloadedTy poly_ty || isInlinePragma inl))  cactus committed Nov 20, 2014 1035  (ptext (sLit "SPECIALISE pragma for non-overloaded function")  Simon Peyton Jones committed Nov 22, 2013 1036  <+> quotes (ppr fun_name))  <