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)))
249 nlWildPat = noLoc (WildPat placeHolderType) -- Pre-typechecking
251 nlHsDo :: HsStmtContext Name -> [LStmt id] -> LHsExpr id -> LHsExpr id
252 nlHsDo ctxt stmts body = noLoc (mkHsDo ctxt stmts body)
254 nlHsOpApp :: LHsExpr id -> id -> LHsExpr id -> LHsExpr id
255 nlHsOpApp e1 op e2 = noLoc (mkHsOpApp e1 op e2)
257 nlHsLam :: LMatch id -> LHsExpr id
258 nlHsPar :: LHsExpr id -> LHsExpr id
259 nlHsIf :: LHsExpr id -> LHsExpr id -> LHsExpr id -> LHsExpr id
260 nlHsCase :: LHsExpr id -> [LMatch id] -> LHsExpr id
261 nlList :: [LHsExpr id] -> LHsExpr id
263 nlHsLam match = noLoc (HsLam (mkMatchGroup [match]))
264 nlHsPar e = noLoc (HsPar e)
265 nlHsIf cond true false = noLoc (HsIf cond true false)
266 nlHsCase expr matches = noLoc (HsCase expr (mkMatchGroup matches))
267 nlList exprs = noLoc (ExplicitList placeHolderType exprs)
269 nlHsAppTy :: LHsType name -> LHsType name -> LHsType name
270 nlHsTyVar :: name -> LHsType name
271 nlHsFunTy :: LHsType name -> LHsType name -> LHsType name
273 nlHsAppTy f t = noLoc (HsAppTy f t)
274 nlHsTyVar x = noLoc (HsTyVar x)
275 nlHsFunTy a b = noLoc (HsFunTy a b)
277 nlHsTyConApp :: name -> [LHsType name] -> LHsType name
278 nlHsTyConApp tycon tys = foldl nlHsAppTy (nlHsTyVar tycon) tys
281 Tuples. All these functions are *pre-typechecker* because they lack
285 mkLHsTupleExpr :: [LHsExpr a] -> LHsExpr a
286 -- Makes a pre-typechecker boxed tuple, deals with 1 case
287 mkLHsTupleExpr [e] = e
288 mkLHsTupleExpr es = noLoc $ ExplicitTuple (map Present es) Boxed
290 mkLHsVarTuple :: [a] -> LHsExpr a
291 mkLHsVarTuple ids = mkLHsTupleExpr (map nlHsVar ids)
293 nlTuplePat :: [LPat id] -> Boxity -> LPat id
294 nlTuplePat pats box = noLoc (TuplePat pats box placeHolderType)
296 missingTupArg :: HsTupArg a
297 missingTupArg = Missing placeHolderType
300 %************************************************************************
302 Bindings; with a location at the top
304 %************************************************************************
307 mkFunBind :: Located id -> [LMatch id] -> HsBind id
308 -- Not infix, with place holders for coercion and free vars
309 mkFunBind fn ms = FunBind { fun_id = fn, fun_infix = False, fun_matches = mkMatchGroup ms,
310 fun_co_fn = idHsWrapper, bind_fvs = placeHolderNames,
314 mkVarBind :: SrcSpan -> id -> LHsExpr id -> LHsBind id
315 mkVarBind loc var rhs = mk_easy_FunBind loc var [] rhs
318 mk_easy_FunBind :: SrcSpan -> id -> [LPat id]
319 -> LHsExpr id -> LHsBind id
321 mk_easy_FunBind loc fun pats expr
322 = L loc $ mkFunBind (L loc fun) [mkMatch pats expr emptyLocalBinds]
325 mk_FunBind :: SrcSpan -> id
326 -> [([LPat id], LHsExpr id)]
329 mk_FunBind _ _ [] = panic "TcGenDeriv:mk_FunBind"
330 mk_FunBind loc fun pats_and_exprs
331 = L loc $ mkFunBind (L loc fun) matches
333 matches = [mkMatch p e emptyLocalBinds | (p,e) <-pats_and_exprs]
336 mkMatch :: [LPat id] -> LHsExpr id -> HsLocalBinds id -> LMatch id
337 mkMatch pats expr binds
338 = noLoc (Match (map paren pats) Nothing
339 (GRHSs (unguardedRHS expr) binds))
341 paren lp@(L l p) | hsPatNeedsParens p = L l (ParPat lp)
346 %************************************************************************
348 Collecting binders from HsBindGroups and HsBinds
350 %************************************************************************
352 Get all the binders in some HsBindGroups, IN THE ORDER OF APPEARANCE. eg.
360 it should return [x, y, f, a, b] (remember, order important).
363 collectLocalBinders :: HsLocalBindsLR idL idR -> [Located idL]
364 collectLocalBinders (HsValBinds val_binds) = collectHsValBinders val_binds
365 collectLocalBinders (HsIPBinds _) = []
366 collectLocalBinders EmptyLocalBinds = []
368 collectHsValBinders :: HsValBindsLR idL idR -> [Located idL]
369 collectHsValBinders (ValBindsIn binds _) = collectHsBindLocatedBinders binds
370 collectHsValBinders (ValBindsOut binds _) = foldr collect_one [] binds
372 collect_one (_,binds) acc = foldrBag (collectAcc . unLoc) acc binds
374 collectAcc :: HsBindLR idL idR -> [Located idL] -> [Located idL]
375 collectAcc (PatBind { pat_lhs = p }) acc = collectLocatedPatBinders p ++ acc
376 collectAcc (FunBind { fun_id = f }) acc = f : acc
377 collectAcc (VarBind { var_id = f }) acc = noLoc f : acc
378 collectAcc (AbsBinds { abs_exports = dbinds, abs_binds = _binds }) acc
379 = [noLoc dp | (_,dp,_,_) <- dbinds] ++ acc
380 -- ++ foldr collectAcc acc binds
381 -- I don't think we want the binders from the nested binds
382 -- The only time we collect binders from a typechecked
383 -- binding (hence see AbsBinds) is in zonking in TcHsSyn
385 collectHsBindBinders :: LHsBindsLR idL idR -> [idL]
386 collectHsBindBinders binds = map unLoc (collectHsBindLocatedBinders binds)
388 collectHsBindLocatedBinders :: LHsBindsLR idL idR -> [Located idL]
389 collectHsBindLocatedBinders binds = foldrBag (collectAcc . unLoc) [] binds
393 %************************************************************************
395 Getting binders from statements
397 %************************************************************************
400 collectLStmtsBinders :: [LStmtLR idL idR] -> [Located idL]
401 collectLStmtsBinders = concatMap collectLStmtBinders
403 collectStmtsBinders :: [StmtLR idL idR] -> [Located idL]
404 collectStmtsBinders = concatMap collectStmtBinders
406 collectLStmtBinders :: LStmtLR idL idR -> [Located idL]
407 collectLStmtBinders = collectStmtBinders . unLoc
409 collectStmtBinders :: StmtLR idL idR -> [Located idL]
410 -- Id Binders for a Stmt... [but what about pattern-sig type vars]?
411 collectStmtBinders (BindStmt pat _ _ _) = collectLocatedPatBinders pat
412 collectStmtBinders (LetStmt binds) = collectLocalBinders binds
413 collectStmtBinders (ExprStmt _ _ _) = []
414 collectStmtBinders (ParStmt xs) = collectLStmtsBinders
416 collectStmtBinders (TransformStmt (stmts, _) _ _) = collectLStmtsBinders stmts
417 collectStmtBinders (GroupStmt (stmts, _) _) = collectLStmtsBinders stmts
418 collectStmtBinders (RecStmt ss _ _ _ _) = collectLStmtsBinders ss
422 %************************************************************************
424 %* Gathering stuff out of patterns
426 %************************************************************************
428 This function @collectPatBinders@ works with the ``collectBinders''
429 functions for @HsBinds@, etc. The order in which the binders are
430 collected is important; see @HsBinds.lhs@.
432 It collects the bounds *value* variables in renamed patterns; type variables
436 collectPatBinders :: LPat a -> [a]
437 collectPatBinders pat = map unLoc (collectLocatedPatBinders pat)
439 collectLocatedPatBinders :: LPat a -> [Located a]
440 collectLocatedPatBinders pat = collectl pat []
442 collectPatsBinders :: [LPat a] -> [a]
443 collectPatsBinders pats = map unLoc (collectLocatedPatsBinders pats)
445 collectLocatedPatsBinders :: [LPat a] -> [Located a]
446 collectLocatedPatsBinders pats = foldr collectl [] pats
448 ---------------------
449 collectl :: LPat name -> [Located name] -> [Located name]
450 collectl (L l pat) bndrs
453 go (VarPat var) = L l var : bndrs
454 go (VarPatOut var bs) = L l var : collectHsBindLocatedBinders bs
456 go (WildPat _) = bndrs
457 go (LazyPat pat) = collectl pat bndrs
458 go (BangPat pat) = collectl pat bndrs
459 go (AsPat a pat) = a : collectl pat bndrs
460 go (ViewPat _ pat _) = collectl pat bndrs
461 go (ParPat pat) = collectl pat bndrs
463 go (ListPat pats _) = foldr collectl bndrs pats
464 go (PArrPat pats _) = foldr collectl bndrs pats
465 go (TuplePat pats _ _) = foldr collectl bndrs pats
467 go (ConPatIn _ ps) = foldr collectl bndrs (hsConPatArgs ps)
468 go (ConPatOut {pat_args=ps}) = foldr collectl bndrs (hsConPatArgs ps)
469 -- See Note [Dictionary binders in ConPatOut]
470 go (LitPat _) = bndrs
471 go (NPat _ _ _) = bndrs
472 go (NPlusKPat n _ _ _) = n : bndrs
474 go (SigPatIn pat _) = collectl pat bndrs
475 go (SigPatOut pat _) = collectl pat bndrs
476 go (QuasiQuotePat _) = bndrs
477 go (TypePat _) = bndrs
478 go (CoPat _ pat _) = collectl (noLoc pat) bndrs
481 Note [Dictionary binders in ConPatOut]
482 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
483 Do *not* gather (a) dictionary and (b) dictionary bindings as binders
484 of a ConPatOut pattern. For most calls it doesn't matter, because
485 it's pre-typechecker and there are no ConPatOuts. But it does matter
486 more in the desugarer; for example, DsUtils.mkSelectorBinds uses
487 collectPatBinders. In a lazy pattern, for example f ~(C x y) = ...,
488 we want to generate bindings for x,y but not for dictionaries bound by
489 C. (The type checker ensures they would not be used.)
491 Desugaring of arrow case expressions needs these bindings (see DsArrows
492 and arrowcase1), but SPJ (Jan 2007) says it's safer for it to use its
493 own pat-binder-collector:
495 Here's the problem. Consider
498 C :: Num a => a -> Int -> T a
500 f ~(C (n+1) m) = (n,m)
502 Here, the pattern (C (n+1)) binds a hidden dictionary (d::Num a),
503 and *also* uses that dictionary to match the (n+1) pattern. Yet, the
504 variables bound by the lazy pattern are n,m, *not* the dictionary d.
505 So in mkSelectorBinds in DsUtils, we want just m,n as the variables bound.
508 collectSigTysFromPats :: [InPat name] -> [LHsType name]
509 collectSigTysFromPats pats = foldr collect_lpat [] pats
511 collectSigTysFromPat :: InPat name -> [LHsType name]
512 collectSigTysFromPat pat = collect_lpat pat []
514 collect_lpat :: InPat name -> [LHsType name] -> [LHsType name]
515 collect_lpat pat acc = collect_pat (unLoc pat) acc
517 collect_pat :: Pat name -> [LHsType name] -> [LHsType name]
518 collect_pat (SigPatIn pat ty) acc = collect_lpat pat (ty:acc)
519 collect_pat (TypePat ty) acc = ty:acc
521 collect_pat (LazyPat pat) acc = collect_lpat pat acc
522 collect_pat (BangPat pat) acc = collect_lpat pat acc
523 collect_pat (AsPat _ pat) acc = collect_lpat pat acc
524 collect_pat (ParPat pat) acc = collect_lpat pat acc
525 collect_pat (ListPat pats _) acc = foldr collect_lpat acc pats
526 collect_pat (PArrPat pats _) acc = foldr collect_lpat acc pats
527 collect_pat (TuplePat pats _ _) acc = foldr collect_lpat acc pats
528 collect_pat (ConPatIn _ ps) acc = foldr collect_lpat acc (hsConPatArgs ps)
529 collect_pat _ acc = acc -- Literals, vars, wildcard