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
18 #include "HsVersions.h"
41 %************************************************************************
43 Some useful helpers for constructing syntax
45 %************************************************************************
47 These functions attempt to construct a not-completely-useless SrcSpan
48 from their components, compared with the nl* functions below which
49 just attach noSrcSpan to everything.
52 mkHsPar :: LHsExpr id -> LHsExpr id
53 mkHsPar e = L (getLoc e) (HsPar e)
55 mkSimpleMatch :: [LPat id] -> LHsExpr id -> LMatch id
56 mkSimpleMatch pats rhs
58 Match pats Nothing (unguardedGRHSs rhs)
62 (pat:_) -> combineSrcSpans (getLoc pat) (getLoc rhs)
64 unguardedGRHSs :: LHsExpr id -> GRHSs id
65 unguardedGRHSs rhs = GRHSs (unguardedRHS rhs) emptyLocalBinds
67 unguardedRHS :: LHsExpr id -> [LGRHS id]
68 unguardedRHS rhs@(L loc _) = [L loc (GRHS [] rhs)]
70 mkHsAppTy :: LHsType name -> LHsType name -> LHsType name
71 mkHsAppTy t1 t2 = addCLoc t1 t2 (HsAppTy t1 t2)
73 mkHsApp :: LHsExpr name -> LHsExpr name -> LHsExpr name
74 mkHsApp e1 e2 = addCLoc e1 e2 (HsApp e1 e2)
76 nlHsTyApp :: name -> [Type] -> LHsExpr name
77 nlHsTyApp fun_id tys = noLoc (HsWrap (mkWpTyApps tys) (HsVar fun_id))
79 mkLHsWrap :: HsWrapper -> LHsExpr id -> LHsExpr id
80 mkLHsWrap co_fn (L loc e) = L loc (mkHsWrap co_fn e)
82 mkHsWrap :: HsWrapper -> HsExpr id -> HsExpr id
83 mkHsWrap co_fn e | isIdHsWrapper co_fn = e
84 | otherwise = HsWrap co_fn e
86 mkHsLam :: [LPat id] -> LHsExpr id -> LHsExpr id
87 mkHsLam pats body = mkHsPar (L (getLoc body) (HsLam matches))
89 matches = mkMatchGroup [mkSimpleMatch pats body]
91 mkMatchGroup :: [LMatch id] -> MatchGroup id
92 mkMatchGroup matches = MatchGroup matches placeHolderType
94 mkHsDictLet :: LHsBinds Id -> LHsExpr Id -> LHsExpr Id
95 -- Used for the dictionary bindings gotten from TcSimplify
96 -- We make them recursive to be on the safe side
97 mkHsDictLet binds expr
98 | isEmptyLHsBinds binds = expr
99 | otherwise = L (getLoc expr) (HsLet (HsValBinds val_binds) expr)
101 val_binds = ValBindsOut [(Recursive, binds)] []
103 mkHsConApp :: DataCon -> [Type] -> [HsExpr Id] -> LHsExpr Id
104 -- Used for constructing dictinoary terms etc, so no locations
105 mkHsConApp data_con tys args
106 = foldl mk_app (nlHsTyApp (dataConWrapId data_con) tys) args
108 mk_app f a = noLoc (HsApp f (noLoc a))
110 mkSimpleHsAlt :: LPat id -> LHsExpr id -> LMatch id
111 -- A simple lambda with a single pattern, no binds, no guards; pre-typechecking
112 mkSimpleHsAlt pat expr
113 = mkSimpleMatch [pat] expr
115 -------------------------------
116 -- These are the bits of syntax that contain rebindable names
117 -- See RnEnv.lookupSyntaxName
119 mkHsIntegral i = HsIntegral i noSyntaxExpr
120 mkHsFractional f = HsFractional f noSyntaxExpr
121 mkHsDo ctxt stmts body = HsDo ctxt stmts body placeHolderType
123 mkNPat lit neg = NPat lit neg noSyntaxExpr placeHolderType
124 mkNPlusKPat id lit = NPlusKPat id lit noSyntaxExpr noSyntaxExpr
126 mkExprStmt expr = ExprStmt expr noSyntaxExpr placeHolderType
127 mkBindStmt pat expr = BindStmt pat expr noSyntaxExpr noSyntaxExpr
128 mkRecStmt stmts = RecStmt stmts [] [] [] emptyLHsBinds
130 -------------------------------
131 --- A useful function for building @OpApps@. The operator is always a
132 -- variable, and we don't know the fixity yet.
133 mkHsOpApp e1 op e2 = OpApp e1 (noLoc (HsVar op)) (error "mkOpApp:fixity") e2
135 mkHsSplice e = HsSplice unqualSplice e
137 unqualSplice = mkRdrUnqual (mkVarOccFS FSLIT("splice"))
138 -- A name (uniquified later) to
139 -- identify the splice
141 mkHsString s = HsString (mkFastString s)
144 userHsTyVarBndrs :: [Located name] -> [Located (HsTyVarBndr name)]
145 userHsTyVarBndrs bndrs = [ L loc (UserTyVar v) | L loc v <- bndrs ]
149 %************************************************************************
151 Constructing syntax with no location info
153 %************************************************************************
156 nlHsVar :: id -> LHsExpr id
157 nlHsVar n = noLoc (HsVar n)
159 nlHsLit :: HsLit -> LHsExpr id
160 nlHsLit n = noLoc (HsLit n)
162 nlVarPat :: id -> LPat id
163 nlVarPat n = noLoc (VarPat n)
165 nlLitPat :: HsLit -> LPat id
166 nlLitPat l = noLoc (LitPat l)
168 nlHsApp :: LHsExpr id -> LHsExpr id -> LHsExpr id
169 nlHsApp f x = noLoc (HsApp f x)
171 nlHsIntLit n = noLoc (HsLit (HsInt n))
173 nlHsApps :: id -> [LHsExpr id] -> LHsExpr id
174 nlHsApps f xs = foldl nlHsApp (nlHsVar f) xs
176 nlHsVarApps :: id -> [id] -> LHsExpr id
177 nlHsVarApps f xs = noLoc (foldl mk (HsVar f) (map HsVar xs))
179 mk f a = HsApp (noLoc f) (noLoc a)
181 nlConVarPat :: id -> [id] -> LPat id
182 nlConVarPat con vars = nlConPat con (map nlVarPat vars)
184 nlInfixConPat :: id -> LPat id -> LPat id -> LPat id
185 nlInfixConPat con l r = noLoc (ConPatIn (noLoc con) (InfixCon l r))
187 nlConPat :: id -> [LPat id] -> LPat id
188 nlConPat con pats = noLoc (ConPatIn (noLoc con) (PrefixCon pats))
190 nlNullaryConPat :: id -> LPat id
191 nlNullaryConPat con = noLoc (ConPatIn (noLoc con) (PrefixCon []))
193 nlWildConPat :: DataCon -> LPat RdrName
194 nlWildConPat con = noLoc (ConPatIn (noLoc (getRdrName con))
195 (PrefixCon (nOfThem (dataConSourceArity con) nlWildPat)))
197 nlTuplePat pats box = noLoc (TuplePat pats box placeHolderType)
198 nlWildPat = noLoc (WildPat placeHolderType) -- Pre-typechecking
200 nlHsDo :: HsStmtContext Name -> [LStmt id] -> LHsExpr id -> LHsExpr id
201 nlHsDo ctxt stmts body = noLoc (mkHsDo ctxt stmts body)
203 nlHsOpApp e1 op e2 = noLoc (mkHsOpApp e1 op e2)
205 nlHsLam match = noLoc (HsLam (mkMatchGroup [match]))
206 nlHsPar e = noLoc (HsPar e)
207 nlHsIf cond true false = noLoc (HsIf cond true false)
208 nlHsCase expr matches = noLoc (HsCase expr (mkMatchGroup matches))
209 nlTuple exprs box = noLoc (ExplicitTuple exprs box)
210 nlList exprs = noLoc (ExplicitList placeHolderType exprs)
212 nlHsAppTy f t = noLoc (HsAppTy f t)
213 nlHsTyVar x = noLoc (HsTyVar x)
214 nlHsFunTy a b = noLoc (HsFunTy a b)
219 %************************************************************************
221 Bindings; with a location at the top
223 %************************************************************************
226 mkFunBind :: Located id -> [LMatch id] -> HsBind id
227 -- Not infix, with place holders for coercion and free vars
228 mkFunBind fn ms = FunBind { fun_id = fn, fun_infix = False, fun_matches = mkMatchGroup ms,
229 fun_co_fn = idHsWrapper, bind_fvs = placeHolderNames,
233 mkVarBind :: SrcSpan -> RdrName -> LHsExpr RdrName -> LHsBind RdrName
234 mkVarBind loc var rhs = mk_easy_FunBind loc var [] rhs
237 mk_easy_FunBind :: SrcSpan -> RdrName -> [LPat RdrName]
238 -> LHsExpr RdrName -> LHsBind RdrName
240 mk_easy_FunBind loc fun pats expr
241 = L loc $ mkFunBind (L loc fun) [mkMatch pats expr emptyLocalBinds]
244 mk_FunBind :: SrcSpan -> RdrName
245 -> [([LPat RdrName], LHsExpr RdrName)]
248 mk_FunBind loc fun [] = panic "TcGenDeriv:mk_FunBind"
249 mk_FunBind loc fun pats_and_exprs
250 = L loc $ mkFunBind (L loc fun) matches
252 matches = [mkMatch p e emptyLocalBinds | (p,e) <-pats_and_exprs]
255 mkMatch :: [LPat id] -> LHsExpr id -> HsLocalBinds id -> LMatch id
256 mkMatch pats expr binds
257 = noLoc (Match (map paren pats) Nothing
258 (GRHSs (unguardedRHS expr) binds))
262 L l _ -> L l (ParPat p)
266 %************************************************************************
268 Collecting binders from HsBindGroups and HsBinds
270 %************************************************************************
272 Get all the binders in some HsBindGroups, IN THE ORDER OF APPEARANCE. eg.
280 it should return [x, y, f, a, b] (remember, order important).
283 collectLocalBinders :: HsLocalBinds name -> [Located name]
284 collectLocalBinders (HsValBinds val_binds) = collectHsValBinders val_binds
285 collectLocalBinders (HsIPBinds _) = []
286 collectLocalBinders EmptyLocalBinds = []
288 collectHsValBinders :: HsValBinds name -> [Located name]
289 collectHsValBinders (ValBindsIn binds sigs) = collectHsBindLocatedBinders binds
290 collectHsValBinders (ValBindsOut binds sigs) = foldr collect_one [] binds
292 collect_one (_,binds) acc = foldrBag (collectAcc . unLoc) acc binds
294 collectAcc :: HsBind name -> [Located name] -> [Located name]
295 collectAcc (PatBind { pat_lhs = p }) acc = collectLocatedPatBinders p ++ acc
296 collectAcc (FunBind { fun_id = f }) acc = f : acc
297 collectAcc (VarBind { var_id = f }) acc = noLoc f : acc
298 collectAcc (AbsBinds { abs_exports = dbinds, abs_binds = binds }) acc
299 = [noLoc dp | (_,dp,_,_) <- dbinds] ++ acc
300 -- ++ foldr collectAcc acc binds
301 -- I don't think we want the binders from the nested binds
302 -- The only time we collect binders from a typechecked
303 -- binding (hence see AbsBinds) is in zonking in TcHsSyn
305 collectHsBindBinders :: LHsBinds name -> [name]
306 collectHsBindBinders binds = map unLoc (collectHsBindLocatedBinders binds)
308 collectHsBindLocatedBinders :: LHsBinds name -> [Located name]
309 collectHsBindLocatedBinders binds = foldrBag (collectAcc . unLoc) [] binds
313 %************************************************************************
315 Getting binders from statements
317 %************************************************************************
320 collectLStmtsBinders :: [LStmt id] -> [Located id]
321 collectLStmtsBinders = concatMap collectLStmtBinders
323 collectStmtsBinders :: [Stmt id] -> [Located id]
324 collectStmtsBinders = concatMap collectStmtBinders
326 collectLStmtBinders :: LStmt id -> [Located id]
327 collectLStmtBinders = collectStmtBinders . unLoc
329 collectStmtBinders :: Stmt id -> [Located id]
330 -- Id Binders for a Stmt... [but what about pattern-sig type vars]?
331 collectStmtBinders (BindStmt pat _ _ _) = collectLocatedPatBinders pat
332 collectStmtBinders (LetStmt binds) = collectLocalBinders binds
333 collectStmtBinders (ExprStmt _ _ _) = []
334 collectStmtBinders (RecStmt ss _ _ _ _) = collectLStmtsBinders ss
335 collectStmtBinders other = panic "collectStmtBinders"
339 %************************************************************************
341 %* Gathering stuff out of patterns
343 %************************************************************************
345 This function @collectPatBinders@ works with the ``collectBinders''
346 functions for @HsBinds@, etc. The order in which the binders are
347 collected is important; see @HsBinds.lhs@.
349 It collects the bounds *value* variables in renamed patterns; type variables
353 collectPatBinders :: LPat a -> [a]
354 collectPatBinders pat = map unLoc (collectLocatedPatBinders pat)
356 collectLocatedPatBinders :: LPat a -> [Located a]
357 collectLocatedPatBinders pat = collectl pat []
359 collectPatsBinders :: [LPat a] -> [a]
360 collectPatsBinders pats = map unLoc (collectLocatedPatsBinders pats)
362 collectLocatedPatsBinders :: [LPat a] -> [Located a]
363 collectLocatedPatsBinders pats = foldr collectl [] pats
365 ---------------------
366 collectl (L l pat) bndrs
369 go (VarPat var) = L l var : bndrs
370 go (VarPatOut var bs) = L l var : collectHsBindLocatedBinders bs
372 go (WildPat _) = bndrs
373 go (LazyPat pat) = collectl pat bndrs
374 go (BangPat pat) = collectl pat bndrs
375 go (AsPat a pat) = a : collectl pat bndrs
376 go (ParPat pat) = collectl pat bndrs
378 go (ListPat pats _) = foldr collectl bndrs pats
379 go (PArrPat pats _) = foldr collectl bndrs pats
380 go (TuplePat pats _ _) = foldr collectl bndrs pats
382 go (ConPatIn c ps) = foldr collectl bndrs (hsConArgs ps)
383 go (ConPatOut {pat_args=ps}) = foldr collectl bndrs (hsConArgs ps)
384 -- See Note [Dictionary binders in ConPatOut]
385 go (LitPat _) = bndrs
386 go (NPat _ _ _ _) = bndrs
387 go (NPlusKPat n _ _ _) = n : bndrs
389 go (SigPatIn pat _) = collectl pat bndrs
390 go (SigPatOut pat _) = collectl pat bndrs
391 go (TypePat ty) = bndrs
392 go (DictPat ids1 ids2) = map noLoc ids1 ++ map noLoc ids2
394 go (CoPat _ pat ty) = collectl (noLoc pat) bndrs
397 Note [Dictionary binders in ConPatOut]
398 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
399 Do *not* gather (a) dictionary and (b) dictionary bindings as binders
400 of a ConPatOut pattern. For most calls it doesn't matter, because
401 it's pre-typechecker and there are no ConPatOuts. But it does matter
402 more in the desugarer; for example, DsUtils.mkSelectorBinds uses
403 collectPatBinders. In a lazy pattern, for example f ~(C x y) = ...,
404 we want to generate bindings for x,y but not for dictionaries bound by
405 C. (The type checker ensures they would not be used.)
408 collectSigTysFromPats :: [InPat name] -> [LHsType name]
409 collectSigTysFromPats pats = foldr collect_lpat [] pats
411 collectSigTysFromPat :: InPat name -> [LHsType name]
412 collectSigTysFromPat pat = collect_lpat pat []
414 collect_lpat pat acc = collect_pat (unLoc pat) acc
416 collect_pat (SigPatIn pat ty) acc = collect_lpat pat (ty:acc)
417 collect_pat (TypePat ty) acc = ty:acc
419 collect_pat (LazyPat pat) acc = collect_lpat pat acc
420 collect_pat (BangPat pat) acc = collect_lpat pat acc
421 collect_pat (AsPat a pat) acc = collect_lpat pat acc
422 collect_pat (ParPat pat) acc = collect_lpat pat acc
423 collect_pat (ListPat pats _) acc = foldr collect_lpat acc pats
424 collect_pat (PArrPat pats _) acc = foldr collect_lpat acc pats
425 collect_pat (TuplePat pats _ _) acc = foldr collect_lpat acc pats
426 collect_pat (ConPatIn c ps) acc = foldr collect_lpat acc (hsConArgs ps)
427 collect_pat other acc = acc -- Literals, vars, wildcard
430 %************************************************************************
432 %* Getting the main binder name of a top declaration
434 %************************************************************************
438 getMainDeclBinder :: HsDecl name -> Maybe name
439 getMainDeclBinder (TyClD d) = Just (tcdName d)
440 getMainDeclBinder (ValD d)
441 = case collectAcc d [] of
442 [] -> Nothing -- see rn003
443 (name:_) -> Just (unLoc name)
444 getMainDeclBinder (SigD d) = sigNameNoLoc d
445 getMainDeclBinder (ForD (ForeignImport name _ _)) = Just (unLoc name)
446 getMainDeclBinder (ForD (ForeignExport name _ _)) = Just (unLoc name)
447 getMainDeclBinder _ = Nothing