2 % (c) The University of Glasgow, 1992-2006
5 Here we collect a variety of helper functions that construct or
6 analyse HsSyn. All these functions deal with generic HsSyn; functions
7 which deal with the intantiated versions are located elsewhere:
9 Parameterised by Module
10 ---------------- -------------
11 RdrName parser/RdrHsSyn
39 %************************************************************************
41 Some useful helpers for constructing syntax
43 %************************************************************************
45 These functions attempt to construct a not-completely-useless SrcSpan
46 from their components, compared with the nl* functions below which
47 just attach noSrcSpan to everything.
50 mkHsPar :: LHsExpr id -> LHsExpr id
51 mkHsPar e = L (getLoc e) (HsPar e)
53 mkSimpleMatch :: [LPat id] -> LHsExpr id -> LMatch id
54 mkSimpleMatch pats rhs
56 Match pats Nothing (unguardedGRHSs rhs)
60 (pat:_) -> combineSrcSpans (getLoc pat) (getLoc rhs)
62 unguardedGRHSs :: LHsExpr id -> GRHSs id
63 unguardedGRHSs rhs = GRHSs (unguardedRHS rhs) emptyLocalBinds
65 unguardedRHS :: LHsExpr id -> [LGRHS id]
66 unguardedRHS rhs@(L loc _) = [L loc (GRHS [] rhs)]
68 mkHsAppTy :: LHsType name -> LHsType name -> LHsType name
69 mkHsAppTy t1 t2 = addCLoc t1 t2 (HsAppTy t1 t2)
71 mkHsApp :: LHsExpr name -> LHsExpr name -> LHsExpr name
72 mkHsApp e1 e2 = addCLoc e1 e2 (HsApp e1 e2)
74 nlHsTyApp :: name -> [Type] -> LHsExpr name
75 nlHsTyApp fun_id tys = noLoc (HsWrap (mkWpTyApps tys) (HsVar fun_id))
77 mkLHsWrap :: HsWrapper -> LHsExpr id -> LHsExpr id
78 mkLHsWrap co_fn (L loc e) = L loc (mkHsWrap co_fn e)
80 mkHsWrap :: HsWrapper -> HsExpr id -> HsExpr id
81 mkHsWrap co_fn e | isIdHsWrapper co_fn = e
82 | otherwise = HsWrap co_fn e
84 mkHsWrapCoI :: CoercionI -> HsExpr id -> HsExpr id
85 mkHsWrapCoI IdCo e = e
86 mkHsWrapCoI (ACo co) e = mkHsWrap (WpCast co) e
88 coiToHsWrapper :: CoercionI -> HsWrapper
89 coiToHsWrapper IdCo = idHsWrapper
90 coiToHsWrapper (ACo co) = WpCast co
92 mkHsLam :: [LPat id] -> LHsExpr id -> LHsExpr id
93 mkHsLam pats body = mkHsPar (L (getLoc body) (HsLam matches))
95 matches = mkMatchGroup [mkSimpleMatch pats body]
97 mkMatchGroup :: [LMatch id] -> MatchGroup id
98 mkMatchGroup matches = MatchGroup matches placeHolderType
100 mkHsDictLet :: LHsBinds Id -> LHsExpr Id -> LHsExpr Id
101 -- Used for the dictionary bindings gotten from TcSimplify
102 -- We make them recursive to be on the safe side
103 mkHsDictLet binds expr
104 | isEmptyLHsBinds binds = expr
105 | otherwise = L (getLoc expr) (HsLet (HsValBinds val_binds) expr)
107 val_binds = ValBindsOut [(Recursive, binds)] []
109 mkHsConApp :: DataCon -> [Type] -> [HsExpr Id] -> LHsExpr Id
110 -- Used for constructing dictionary terms etc, so no locations
111 mkHsConApp data_con tys args
112 = foldl mk_app (nlHsTyApp (dataConWrapId data_con) tys) args
114 mk_app f a = noLoc (HsApp f (noLoc a))
116 mkSimpleHsAlt :: LPat id -> LHsExpr id -> LMatch id
117 -- A simple lambda with a single pattern, no binds, no guards; pre-typechecking
118 mkSimpleHsAlt pat expr
119 = mkSimpleMatch [pat] expr
121 -------------------------------
122 -- These are the bits of syntax that contain rebindable names
123 -- See RnEnv.lookupSyntaxName
125 mkHsIntegral :: Integer -> PostTcType -> HsOverLit id
126 mkHsFractional :: Rational -> PostTcType -> HsOverLit id
127 mkHsIsString :: FastString -> PostTcType -> HsOverLit id
128 mkHsDo :: HsStmtContext Name -> [LStmt id] -> LHsExpr id -> HsExpr id
130 mkNPat :: HsOverLit id -> Maybe (SyntaxExpr id) -> Pat id
131 mkNPlusKPat :: Located id -> HsOverLit id -> Pat id
133 mkTransformStmt :: [LStmt idL] -> LHsExpr idR -> StmtLR idL idR
134 mkTransformByStmt :: [LStmt idL] -> LHsExpr idR -> LHsExpr idR -> StmtLR idL idR
136 mkGroupUsingStmt :: [LStmt idL] -> LHsExpr idR -> StmtLR idL idR
137 mkGroupByStmt :: [LStmt idL] -> LHsExpr idR -> StmtLR idL idR
138 mkGroupByUsingStmt :: [LStmt idL] -> LHsExpr idR -> LHsExpr idR -> StmtLR idL idR
140 mkExprStmt :: LHsExpr idR -> StmtLR idL idR
141 mkBindStmt :: LPat idL -> LHsExpr idR -> StmtLR idL idR
142 mkRecStmt :: [LStmtLR idL idR] -> StmtLR idL idR
145 mkHsIntegral i = OverLit (HsIntegral i) noRebindableInfo noSyntaxExpr
146 mkHsFractional f = OverLit (HsFractional f) noRebindableInfo noSyntaxExpr
147 mkHsIsString s = OverLit (HsIsString s) noRebindableInfo noSyntaxExpr
149 noRebindableInfo :: Bool
150 noRebindableInfo = error "noRebindableInfo" -- Just another placeholder;
152 mkHsDo ctxt stmts body = HsDo ctxt stmts body placeHolderType
154 mkNPat lit neg = NPat lit neg noSyntaxExpr
155 mkNPlusKPat id lit = NPlusKPat id lit noSyntaxExpr noSyntaxExpr
157 mkTransformStmt stmts usingExpr = TransformStmt (stmts, []) usingExpr Nothing
158 mkTransformByStmt stmts usingExpr byExpr = TransformStmt (stmts, []) usingExpr (Just byExpr)
160 mkGroupUsingStmt stmts usingExpr = GroupStmt (stmts, []) (GroupByNothing usingExpr)
161 mkGroupByStmt stmts byExpr = GroupStmt (stmts, []) (GroupBySomething (Right noSyntaxExpr) byExpr)
162 mkGroupByUsingStmt stmts byExpr usingExpr = GroupStmt (stmts, []) (GroupBySomething (Left usingExpr) byExpr)
164 mkExprStmt expr = ExprStmt expr noSyntaxExpr placeHolderType
165 mkBindStmt pat expr = BindStmt pat expr noSyntaxExpr noSyntaxExpr
166 mkRecStmt stmts = RecStmt stmts [] [] [] emptyLHsBinds
168 -------------------------------
169 --- A useful function for building @OpApps@. The operator is always a
170 -- variable, and we don't know the fixity yet.
171 mkHsOpApp :: LHsExpr id -> id -> LHsExpr id -> HsExpr id
172 mkHsOpApp e1 op e2 = OpApp e1 (noLoc (HsVar op)) (error "mkOpApp:fixity") e2
174 mkHsSplice :: LHsExpr RdrName -> HsSplice RdrName
175 mkHsSplice e = HsSplice unqualSplice e
177 unqualSplice :: RdrName
178 unqualSplice = mkRdrUnqual (mkVarOccFS (fsLit "splice"))
179 -- A name (uniquified later) to
180 -- identify the splice
182 mkHsQuasiQuote :: RdrName -> SrcSpan -> FastString -> HsQuasiQuote RdrName
183 mkHsQuasiQuote quoter span quote = HsQuasiQuote unqualQuasiQuote quoter span quote
185 unqualQuasiQuote :: RdrName
186 unqualQuasiQuote = mkRdrUnqual (mkVarOccFS (fsLit "quasiquote"))
187 -- A name (uniquified later) to
188 -- identify the quasi-quote
190 mkHsString :: String -> HsLit
191 mkHsString s = HsString (mkFastString s)
194 userHsTyVarBndrs :: [Located name] -> [Located (HsTyVarBndr name)]
195 userHsTyVarBndrs bndrs = [ L loc (UserTyVar v) | L loc v <- bndrs ]
199 %************************************************************************
201 Constructing syntax with no location info
203 %************************************************************************
206 nlHsVar :: id -> LHsExpr id
207 nlHsVar n = noLoc (HsVar n)
209 nlHsLit :: HsLit -> LHsExpr id
210 nlHsLit n = noLoc (HsLit n)
212 nlVarPat :: id -> LPat id
213 nlVarPat n = noLoc (VarPat n)
215 nlLitPat :: HsLit -> LPat id
216 nlLitPat l = noLoc (LitPat l)
218 nlHsApp :: LHsExpr id -> LHsExpr id -> LHsExpr id
219 nlHsApp f x = noLoc (HsApp f x)
221 nlHsIntLit :: Integer -> LHsExpr id
222 nlHsIntLit n = noLoc (HsLit (HsInt n))
224 nlHsApps :: id -> [LHsExpr id] -> LHsExpr id
225 nlHsApps f xs = foldl nlHsApp (nlHsVar f) xs
227 nlHsVarApps :: id -> [id] -> LHsExpr id
228 nlHsVarApps f xs = noLoc (foldl mk (HsVar f) (map HsVar xs))
230 mk f a = HsApp (noLoc f) (noLoc a)
232 nlConVarPat :: id -> [id] -> LPat id
233 nlConVarPat con vars = nlConPat con (map nlVarPat vars)
235 nlInfixConPat :: id -> LPat id -> LPat id -> LPat id
236 nlInfixConPat con l r = noLoc (ConPatIn (noLoc con) (InfixCon l r))
238 nlConPat :: id -> [LPat id] -> LPat id
239 nlConPat con pats = noLoc (ConPatIn (noLoc con) (PrefixCon pats))
241 nlNullaryConPat :: id -> LPat id
242 nlNullaryConPat con = noLoc (ConPatIn (noLoc con) (PrefixCon []))
244 nlWildConPat :: DataCon -> LPat RdrName
245 nlWildConPat con = noLoc (ConPatIn (noLoc (getRdrName con))
246 (PrefixCon (nOfThem (dataConSourceArity con) nlWildPat)))
248 nlTuplePat :: [LPat id] -> Boxity -> LPat id
249 nlTuplePat pats box = noLoc (TuplePat pats box placeHolderType)
252 nlWildPat = noLoc (WildPat placeHolderType) -- Pre-typechecking
254 nlHsDo :: HsStmtContext Name -> [LStmt id] -> LHsExpr id -> LHsExpr id
255 nlHsDo ctxt stmts body = noLoc (mkHsDo ctxt stmts body)
257 nlHsOpApp :: LHsExpr id -> id -> LHsExpr id -> LHsExpr id
258 nlHsOpApp e1 op e2 = noLoc (mkHsOpApp e1 op e2)
260 nlHsLam :: LMatch id -> LHsExpr id
261 nlHsPar :: LHsExpr id -> LHsExpr id
262 nlHsIf :: LHsExpr id -> LHsExpr id -> LHsExpr id -> LHsExpr id
263 nlHsCase :: LHsExpr id -> [LMatch id] -> LHsExpr id
264 nlTuple :: [LHsExpr id] -> Boxity -> LHsExpr id
265 nlList :: [LHsExpr id] -> LHsExpr id
267 nlHsLam match = noLoc (HsLam (mkMatchGroup [match]))
268 nlHsPar e = noLoc (HsPar e)
269 nlHsIf cond true false = noLoc (HsIf cond true false)
270 nlHsCase expr matches = noLoc (HsCase expr (mkMatchGroup matches))
271 nlTuple exprs box = noLoc (ExplicitTuple exprs box)
272 nlList exprs = noLoc (ExplicitList placeHolderType exprs)
274 nlHsAppTy :: LHsType name -> LHsType name -> LHsType name
275 nlHsTyVar :: name -> LHsType name
276 nlHsFunTy :: LHsType name -> LHsType name -> LHsType name
278 nlHsAppTy f t = noLoc (HsAppTy f t)
279 nlHsTyVar x = noLoc (HsTyVar x)
280 nlHsFunTy a b = noLoc (HsFunTy a b)
282 nlHsTyConApp :: name -> [LHsType name] -> LHsType name
283 nlHsTyConApp tycon tys = foldl nlHsAppTy (nlHsTyVar tycon) tys
288 %************************************************************************
290 Bindings; with a location at the top
292 %************************************************************************
295 mkFunBind :: Located id -> [LMatch id] -> HsBind id
296 -- Not infix, with place holders for coercion and free vars
297 mkFunBind fn ms = FunBind { fun_id = fn, fun_infix = False, fun_matches = mkMatchGroup ms,
298 fun_co_fn = idHsWrapper, bind_fvs = placeHolderNames,
302 mkVarBind :: SrcSpan -> id -> LHsExpr id -> LHsBind id
303 mkVarBind loc var rhs = mk_easy_FunBind loc var [] rhs
306 mk_easy_FunBind :: SrcSpan -> id -> [LPat id]
307 -> LHsExpr id -> LHsBind id
309 mk_easy_FunBind loc fun pats expr
310 = L loc $ mkFunBind (L loc fun) [mkMatch pats expr emptyLocalBinds]
313 mk_FunBind :: SrcSpan -> id
314 -> [([LPat id], LHsExpr id)]
317 mk_FunBind _ _ [] = panic "TcGenDeriv:mk_FunBind"
318 mk_FunBind loc fun pats_and_exprs
319 = L loc $ mkFunBind (L loc fun) matches
321 matches = [mkMatch p e emptyLocalBinds | (p,e) <-pats_and_exprs]
324 mkMatch :: [LPat id] -> LHsExpr id -> HsLocalBinds id -> LMatch id
325 mkMatch pats expr binds
326 = noLoc (Match (map paren pats) Nothing
327 (GRHSs (unguardedRHS expr) binds))
331 L l _ -> L l (ParPat p)
335 %************************************************************************
337 Collecting binders from HsBindGroups and HsBinds
339 %************************************************************************
341 Get all the binders in some HsBindGroups, IN THE ORDER OF APPEARANCE. eg.
349 it should return [x, y, f, a, b] (remember, order important).
352 collectLocalBinders :: HsLocalBindsLR idL idR -> [Located idL]
353 collectLocalBinders (HsValBinds val_binds) = collectHsValBinders val_binds
354 collectLocalBinders (HsIPBinds _) = []
355 collectLocalBinders EmptyLocalBinds = []
357 collectHsValBinders :: HsValBindsLR idL idR -> [Located idL]
358 collectHsValBinders (ValBindsIn binds _) = collectHsBindLocatedBinders binds
359 collectHsValBinders (ValBindsOut binds _) = foldr collect_one [] binds
361 collect_one (_,binds) acc = foldrBag (collectAcc . unLoc) acc binds
363 collectAcc :: HsBindLR idL idR -> [Located idL] -> [Located idL]
364 collectAcc (PatBind { pat_lhs = p }) acc = collectLocatedPatBinders p ++ acc
365 collectAcc (FunBind { fun_id = f }) acc = f : acc
366 collectAcc (VarBind { var_id = f }) acc = noLoc f : acc
367 collectAcc (AbsBinds { abs_exports = dbinds, abs_binds = _binds }) acc
368 = [noLoc dp | (_,dp,_,_) <- dbinds] ++ acc
369 -- ++ foldr collectAcc acc binds
370 -- I don't think we want the binders from the nested binds
371 -- The only time we collect binders from a typechecked
372 -- binding (hence see AbsBinds) is in zonking in TcHsSyn
374 collectHsBindBinders :: LHsBindsLR idL idR -> [idL]
375 collectHsBindBinders binds = map unLoc (collectHsBindLocatedBinders binds)
377 collectHsBindLocatedBinders :: LHsBindsLR idL idR -> [Located idL]
378 collectHsBindLocatedBinders binds = foldrBag (collectAcc . unLoc) [] binds
382 %************************************************************************
384 Getting binders from statements
386 %************************************************************************
389 collectLStmtsBinders :: [LStmtLR idL idR] -> [Located idL]
390 collectLStmtsBinders = concatMap collectLStmtBinders
392 collectStmtsBinders :: [StmtLR idL idR] -> [Located idL]
393 collectStmtsBinders = concatMap collectStmtBinders
395 collectLStmtBinders :: LStmtLR idL idR -> [Located idL]
396 collectLStmtBinders = collectStmtBinders . unLoc
398 collectStmtBinders :: StmtLR idL idR -> [Located idL]
399 -- Id Binders for a Stmt... [but what about pattern-sig type vars]?
400 collectStmtBinders (BindStmt pat _ _ _) = collectLocatedPatBinders pat
401 collectStmtBinders (LetStmt binds) = collectLocalBinders binds
402 collectStmtBinders (ExprStmt _ _ _) = []
403 collectStmtBinders (ParStmt xs) = collectLStmtsBinders
405 collectStmtBinders (TransformStmt (stmts, _) _ _) = collectLStmtsBinders stmts
406 collectStmtBinders (GroupStmt (stmts, _) _) = collectLStmtsBinders stmts
407 collectStmtBinders (RecStmt ss _ _ _ _) = collectLStmtsBinders ss
411 %************************************************************************
413 %* Gathering stuff out of patterns
415 %************************************************************************
417 This function @collectPatBinders@ works with the ``collectBinders''
418 functions for @HsBinds@, etc. The order in which the binders are
419 collected is important; see @HsBinds.lhs@.
421 It collects the bounds *value* variables in renamed patterns; type variables
425 collectPatBinders :: LPat a -> [a]
426 collectPatBinders pat = map unLoc (collectLocatedPatBinders pat)
428 collectLocatedPatBinders :: LPat a -> [Located a]
429 collectLocatedPatBinders pat = collectl pat []
431 collectPatsBinders :: [LPat a] -> [a]
432 collectPatsBinders pats = map unLoc (collectLocatedPatsBinders pats)
434 collectLocatedPatsBinders :: [LPat a] -> [Located a]
435 collectLocatedPatsBinders pats = foldr collectl [] pats
437 ---------------------
438 collectl :: LPat name -> [Located name] -> [Located name]
439 collectl (L l pat) bndrs
442 go (VarPat var) = L l var : bndrs
443 go (VarPatOut var bs) = L l var : collectHsBindLocatedBinders bs
445 go (WildPat _) = bndrs
446 go (LazyPat pat) = collectl pat bndrs
447 go (BangPat pat) = collectl pat bndrs
448 go (AsPat a pat) = a : collectl pat bndrs
449 go (ViewPat _ pat _) = collectl pat bndrs
450 go (ParPat pat) = collectl pat bndrs
452 go (ListPat pats _) = foldr collectl bndrs pats
453 go (PArrPat pats _) = foldr collectl bndrs pats
454 go (TuplePat pats _ _) = foldr collectl bndrs pats
456 go (ConPatIn _ ps) = foldr collectl bndrs (hsConPatArgs ps)
457 go (ConPatOut {pat_args=ps}) = foldr collectl bndrs (hsConPatArgs ps)
458 -- See Note [Dictionary binders in ConPatOut]
459 go (LitPat _) = bndrs
460 go (NPat _ _ _) = bndrs
461 go (NPlusKPat n _ _ _) = n : bndrs
463 go (SigPatIn pat _) = collectl pat bndrs
464 go (SigPatOut pat _) = collectl pat bndrs
465 go (QuasiQuotePat _) = bndrs
466 go (TypePat _) = bndrs
467 go (CoPat _ pat _) = collectl (noLoc pat) bndrs
470 Note [Dictionary binders in ConPatOut]
471 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
472 Do *not* gather (a) dictionary and (b) dictionary bindings as binders
473 of a ConPatOut pattern. For most calls it doesn't matter, because
474 it's pre-typechecker and there are no ConPatOuts. But it does matter
475 more in the desugarer; for example, DsUtils.mkSelectorBinds uses
476 collectPatBinders. In a lazy pattern, for example f ~(C x y) = ...,
477 we want to generate bindings for x,y but not for dictionaries bound by
478 C. (The type checker ensures they would not be used.)
480 Desugaring of arrow case expressions needs these bindings (see DsArrows
481 and arrowcase1), but SPJ (Jan 2007) says it's safer for it to use its
482 own pat-binder-collector:
484 Here's the problem. Consider
487 C :: Num a => a -> Int -> T a
489 f ~(C (n+1) m) = (n,m)
491 Here, the pattern (C (n+1)) binds a hidden dictionary (d::Num a),
492 and *also* uses that dictionary to match the (n+1) pattern. Yet, the
493 variables bound by the lazy pattern are n,m, *not* the dictionary d.
494 So in mkSelectorBinds in DsUtils, we want just m,n as the variables bound.
497 collectSigTysFromPats :: [InPat name] -> [LHsType name]
498 collectSigTysFromPats pats = foldr collect_lpat [] pats
500 collectSigTysFromPat :: InPat name -> [LHsType name]
501 collectSigTysFromPat pat = collect_lpat pat []
503 collect_lpat :: InPat name -> [LHsType name] -> [LHsType name]
504 collect_lpat pat acc = collect_pat (unLoc pat) acc
506 collect_pat :: Pat name -> [LHsType name] -> [LHsType name]
507 collect_pat (SigPatIn pat ty) acc = collect_lpat pat (ty:acc)
508 collect_pat (TypePat ty) acc = ty:acc
510 collect_pat (LazyPat pat) acc = collect_lpat pat acc
511 collect_pat (BangPat pat) acc = collect_lpat pat acc
512 collect_pat (AsPat _ pat) acc = collect_lpat pat acc
513 collect_pat (ParPat pat) acc = collect_lpat pat acc
514 collect_pat (ListPat pats _) acc = foldr collect_lpat acc pats
515 collect_pat (PArrPat pats _) acc = foldr collect_lpat acc pats
516 collect_pat (TuplePat pats _ _) acc = foldr collect_lpat acc pats
517 collect_pat (ConPatIn _ ps) acc = foldr collect_lpat acc (hsConPatArgs ps)
518 collect_pat _ acc = acc -- Literals, vars, wildcard