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"
40 %************************************************************************
42 Some useful helpers for constructing syntax
44 %************************************************************************
46 These functions attempt to construct a not-completely-useless SrcSpan
47 from their components, compared with the nl* functions below which
48 just attach noSrcSpan to everything.
51 mkHsPar :: LHsExpr id -> LHsExpr id
52 mkHsPar e = L (getLoc e) (HsPar e)
54 mkSimpleMatch :: [LPat id] -> LHsExpr id -> LMatch id
55 mkSimpleMatch pats rhs
57 Match pats Nothing (unguardedGRHSs rhs)
61 (pat:_) -> combineSrcSpans (getLoc pat) (getLoc rhs)
63 unguardedGRHSs :: LHsExpr id -> GRHSs id
64 unguardedGRHSs rhs = GRHSs (unguardedRHS rhs) emptyLocalBinds
66 unguardedRHS :: LHsExpr id -> [LGRHS id]
67 unguardedRHS rhs@(L loc _) = [L loc (GRHS [] rhs)]
69 mkHsAppTy :: LHsType name -> LHsType name -> LHsType name
70 mkHsAppTy t1 t2 = addCLoc t1 t2 (HsAppTy t1 t2)
72 mkHsApp :: LHsExpr name -> LHsExpr name -> LHsExpr name
73 mkHsApp e1 e2 = addCLoc e1 e2 (HsApp e1 e2)
75 nlHsTyApp :: name -> [Type] -> LHsExpr name
76 nlHsTyApp fun_id tys = noLoc (HsWrap (mkWpTyApps tys) (HsVar fun_id))
78 mkLHsWrap :: HsWrapper -> LHsExpr id -> LHsExpr id
79 mkLHsWrap co_fn (L loc e) = L loc (mkHsWrap co_fn e)
81 mkHsWrap :: HsWrapper -> HsExpr id -> HsExpr id
82 mkHsWrap co_fn e | isIdHsWrapper co_fn = e
83 | otherwise = HsWrap co_fn e
85 mkHsLam :: [LPat id] -> LHsExpr id -> LHsExpr id
86 mkHsLam pats body = mkHsPar (L (getLoc body) (HsLam matches))
88 matches = mkMatchGroup [mkSimpleMatch pats body]
90 mkMatchGroup :: [LMatch id] -> MatchGroup id
91 mkMatchGroup matches = MatchGroup matches placeHolderType
93 mkHsDictLet :: LHsBinds Id -> LHsExpr Id -> LHsExpr Id
94 -- Used for the dictionary bindings gotten from TcSimplify
95 -- We make them recursive to be on the safe side
96 mkHsDictLet binds expr
97 | isEmptyLHsBinds binds = expr
98 | otherwise = L (getLoc expr) (HsLet (HsValBinds val_binds) expr)
100 val_binds = ValBindsOut [(Recursive, binds)] []
102 mkHsConApp :: DataCon -> [Type] -> [HsExpr Id] -> LHsExpr Id
103 -- Used for constructing dictinoary terms etc, so no locations
104 mkHsConApp data_con tys args
105 = foldl mk_app (nlHsTyApp (dataConWrapId data_con) tys) args
107 mk_app f a = noLoc (HsApp f (noLoc a))
109 mkSimpleHsAlt :: LPat id -> LHsExpr id -> LMatch id
110 -- A simple lambda with a single pattern, no binds, no guards; pre-typechecking
111 mkSimpleHsAlt pat expr
112 = mkSimpleMatch [pat] expr
114 -------------------------------
115 -- These are the bits of syntax that contain rebindable names
116 -- See RnEnv.lookupSyntaxName
118 mkHsIntegral i = HsIntegral i noSyntaxExpr
119 mkHsFractional f = HsFractional f noSyntaxExpr
120 mkHsIsString s = HsIsString s 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)
216 nlHsTyConApp tycon tys = foldl nlHsAppTy (nlHsTyVar tycon) tys
221 %************************************************************************
223 Bindings; with a location at the top
225 %************************************************************************
228 mkFunBind :: Located id -> [LMatch id] -> HsBind id
229 -- Not infix, with place holders for coercion and free vars
230 mkFunBind fn ms = FunBind { fun_id = fn, fun_infix = False, fun_matches = mkMatchGroup ms,
231 fun_co_fn = idHsWrapper, bind_fvs = placeHolderNames,
235 mkVarBind :: SrcSpan -> RdrName -> LHsExpr RdrName -> LHsBind RdrName
236 mkVarBind loc var rhs = mk_easy_FunBind loc var [] rhs
239 mk_easy_FunBind :: SrcSpan -> RdrName -> [LPat RdrName]
240 -> LHsExpr RdrName -> LHsBind RdrName
242 mk_easy_FunBind loc fun pats expr
243 = L loc $ mkFunBind (L loc fun) [mkMatch pats expr emptyLocalBinds]
246 mk_FunBind :: SrcSpan -> RdrName
247 -> [([LPat RdrName], LHsExpr RdrName)]
250 mk_FunBind loc fun [] = panic "TcGenDeriv:mk_FunBind"
251 mk_FunBind loc fun pats_and_exprs
252 = L loc $ mkFunBind (L loc fun) matches
254 matches = [mkMatch p e emptyLocalBinds | (p,e) <-pats_and_exprs]
257 mkMatch :: [LPat id] -> LHsExpr id -> HsLocalBinds id -> LMatch id
258 mkMatch pats expr binds
259 = noLoc (Match (map paren pats) Nothing
260 (GRHSs (unguardedRHS expr) binds))
264 L l _ -> L l (ParPat p)
268 %************************************************************************
270 Collecting binders from HsBindGroups and HsBinds
272 %************************************************************************
274 Get all the binders in some HsBindGroups, IN THE ORDER OF APPEARANCE. eg.
282 it should return [x, y, f, a, b] (remember, order important).
285 collectLocalBinders :: HsLocalBinds name -> [Located name]
286 collectLocalBinders (HsValBinds val_binds) = collectHsValBinders val_binds
287 collectLocalBinders (HsIPBinds _) = []
288 collectLocalBinders EmptyLocalBinds = []
290 collectHsValBinders :: HsValBinds name -> [Located name]
291 collectHsValBinders (ValBindsIn binds sigs) = collectHsBindLocatedBinders binds
292 collectHsValBinders (ValBindsOut binds sigs) = foldr collect_one [] binds
294 collect_one (_,binds) acc = foldrBag (collectAcc . unLoc) acc binds
296 collectAcc :: HsBind name -> [Located name] -> [Located name]
297 collectAcc (PatBind { pat_lhs = p }) acc = collectLocatedPatBinders p ++ acc
298 collectAcc (FunBind { fun_id = f }) acc = f : acc
299 collectAcc (VarBind { var_id = f }) acc = noLoc f : acc
300 collectAcc (AbsBinds { abs_exports = dbinds, abs_binds = binds }) acc
301 = [noLoc dp | (_,dp,_,_) <- dbinds] ++ acc
302 -- ++ foldr collectAcc acc binds
303 -- I don't think we want the binders from the nested binds
304 -- The only time we collect binders from a typechecked
305 -- binding (hence see AbsBinds) is in zonking in TcHsSyn
307 collectHsBindBinders :: LHsBinds name -> [name]
308 collectHsBindBinders binds = map unLoc (collectHsBindLocatedBinders binds)
310 collectHsBindLocatedBinders :: LHsBinds name -> [Located name]
311 collectHsBindLocatedBinders binds = foldrBag (collectAcc . unLoc) [] binds
315 %************************************************************************
317 Getting binders from statements
319 %************************************************************************
322 collectLStmtsBinders :: OutputableBndr id => [LStmt id] -> [Located id]
323 collectLStmtsBinders = concatMap collectLStmtBinders
325 collectStmtsBinders :: OutputableBndr id => [Stmt id] -> [Located id]
326 collectStmtsBinders = concatMap collectStmtBinders
328 collectLStmtBinders :: OutputableBndr id => LStmt id -> [Located id]
329 collectLStmtBinders = collectStmtBinders . unLoc
331 collectStmtBinders :: OutputableBndr id => Stmt id -> [Located id]
332 -- Id Binders for a Stmt... [but what about pattern-sig type vars]?
333 collectStmtBinders (BindStmt pat _ _ _) = collectLocatedPatBinders pat
334 collectStmtBinders (LetStmt binds) = collectLocalBinders binds
335 collectStmtBinders (ExprStmt _ _ _) = []
336 collectStmtBinders (ParStmt xs) = collectLStmtsBinders
338 collectStmtBinders (RecStmt ss _ _ _ _) = collectLStmtsBinders ss
339 collectStmtBinders s = pprPanic "collectStmtBinders" (ppr s)
343 %************************************************************************
345 %* Gathering stuff out of patterns
347 %************************************************************************
349 This function @collectPatBinders@ works with the ``collectBinders''
350 functions for @HsBinds@, etc. The order in which the binders are
351 collected is important; see @HsBinds.lhs@.
353 It collects the bounds *value* variables in renamed patterns; type variables
357 collectPatBinders :: LPat a -> [a]
358 collectPatBinders pat = map unLoc (collectLocatedPatBinders pat)
360 collectLocatedPatBinders :: LPat a -> [Located a]
361 collectLocatedPatBinders pat = collectl pat []
363 collectPatsBinders :: [LPat a] -> [a]
364 collectPatsBinders pats = map unLoc (collectLocatedPatsBinders pats)
366 collectLocatedPatsBinders :: [LPat a] -> [Located a]
367 collectLocatedPatsBinders pats = foldr collectl [] pats
369 ---------------------
370 collectl (L l pat) bndrs
373 go (VarPat var) = L l var : bndrs
374 go (VarPatOut var bs) = L l var : collectHsBindLocatedBinders bs
376 go (WildPat _) = bndrs
377 go (LazyPat pat) = collectl pat bndrs
378 go (BangPat pat) = collectl pat bndrs
379 go (AsPat a pat) = a : collectl pat bndrs
380 go (ParPat pat) = collectl pat bndrs
382 go (ListPat pats _) = foldr collectl bndrs pats
383 go (PArrPat pats _) = foldr collectl bndrs pats
384 go (TuplePat pats _ _) = foldr collectl bndrs pats
386 go (ConPatIn c ps) = foldr collectl bndrs (hsConArgs ps)
387 go (ConPatOut {pat_args=ps}) = foldr collectl bndrs (hsConArgs ps)
388 -- See Note [Dictionary binders in ConPatOut]
389 go (LitPat _) = bndrs
390 go (NPat _ _ _ _) = bndrs
391 go (NPlusKPat n _ _ _) = n : bndrs
393 go (SigPatIn pat _) = collectl pat bndrs
394 go (SigPatOut pat _) = collectl pat bndrs
395 go (TypePat ty) = bndrs
396 go (DictPat ids1 ids2) = map noLoc ids1 ++ map noLoc ids2
398 go (CoPat _ pat ty) = collectl (noLoc pat) bndrs
401 Note [Dictionary binders in ConPatOut]
402 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
403 Do *not* gather (a) dictionary and (b) dictionary bindings as binders
404 of a ConPatOut pattern. For most calls it doesn't matter, because
405 it's pre-typechecker and there are no ConPatOuts. But it does matter
406 more in the desugarer; for example, DsUtils.mkSelectorBinds uses
407 collectPatBinders. In a lazy pattern, for example f ~(C x y) = ...,
408 we want to generate bindings for x,y but not for dictionaries bound by
409 C. (The type checker ensures they would not be used.)
412 collectSigTysFromPats :: [InPat name] -> [LHsType name]
413 collectSigTysFromPats pats = foldr collect_lpat [] pats
415 collectSigTysFromPat :: InPat name -> [LHsType name]
416 collectSigTysFromPat pat = collect_lpat pat []
418 collect_lpat pat acc = collect_pat (unLoc pat) acc
420 collect_pat (SigPatIn pat ty) acc = collect_lpat pat (ty:acc)
421 collect_pat (TypePat ty) acc = ty:acc
423 collect_pat (LazyPat pat) acc = collect_lpat pat acc
424 collect_pat (BangPat pat) acc = collect_lpat pat acc
425 collect_pat (AsPat a pat) acc = collect_lpat pat acc
426 collect_pat (ParPat pat) acc = collect_lpat pat acc
427 collect_pat (ListPat pats _) acc = foldr collect_lpat acc pats
428 collect_pat (PArrPat pats _) acc = foldr collect_lpat acc pats
429 collect_pat (TuplePat pats _ _) acc = foldr collect_lpat acc pats
430 collect_pat (ConPatIn c ps) acc = foldr collect_lpat acc (hsConArgs ps)
431 collect_pat other acc = acc -- Literals, vars, wildcard