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
17 -- The above warning supression flag is a temporary kludge.
18 -- While working on this module you are encouraged to remove it and fix
19 -- any warnings in the module. See
20 -- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
25 #include "HsVersions.h"
48 %************************************************************************
50 Some useful helpers for constructing syntax
52 %************************************************************************
54 These functions attempt to construct a not-completely-useless SrcSpan
55 from their components, compared with the nl* functions below which
56 just attach noSrcSpan to everything.
59 mkHsPar :: LHsExpr id -> LHsExpr id
60 mkHsPar e = L (getLoc e) (HsPar e)
62 mkSimpleMatch :: [LPat id] -> LHsExpr id -> LMatch id
63 mkSimpleMatch pats rhs
65 Match pats Nothing (unguardedGRHSs rhs)
69 (pat:_) -> combineSrcSpans (getLoc pat) (getLoc rhs)
71 unguardedGRHSs :: LHsExpr id -> GRHSs id
72 unguardedGRHSs rhs = GRHSs (unguardedRHS rhs) emptyLocalBinds
74 unguardedRHS :: LHsExpr id -> [LGRHS id]
75 unguardedRHS rhs@(L loc _) = [L loc (GRHS [] rhs)]
77 mkHsAppTy :: LHsType name -> LHsType name -> LHsType name
78 mkHsAppTy t1 t2 = addCLoc t1 t2 (HsAppTy t1 t2)
80 mkHsApp :: LHsExpr name -> LHsExpr name -> LHsExpr name
81 mkHsApp e1 e2 = addCLoc e1 e2 (HsApp e1 e2)
83 nlHsTyApp :: name -> [Type] -> LHsExpr name
84 nlHsTyApp fun_id tys = noLoc (HsWrap (mkWpTyApps tys) (HsVar fun_id))
86 mkLHsWrap :: HsWrapper -> LHsExpr id -> LHsExpr id
87 mkLHsWrap co_fn (L loc e) = L loc (mkHsWrap co_fn e)
89 mkHsWrap :: HsWrapper -> HsExpr id -> HsExpr id
90 mkHsWrap co_fn e | isIdHsWrapper co_fn = e
91 | otherwise = HsWrap co_fn e
93 mkHsWrapCoI :: CoercionI -> HsExpr id -> HsExpr id
94 mkHsWrapCoI IdCo e = e
95 mkHsWrapCoI (ACo co) e = mkHsWrap (WpCo co) e
97 coiToHsWrapper :: CoercionI -> HsWrapper
98 coiToHsWrapper IdCo = idHsWrapper
99 coiToHsWrapper (ACo co) = WpCo co
101 mkHsLam :: [LPat id] -> LHsExpr id -> LHsExpr id
102 mkHsLam pats body = mkHsPar (L (getLoc body) (HsLam matches))
104 matches = mkMatchGroup [mkSimpleMatch pats body]
106 mkMatchGroup :: [LMatch id] -> MatchGroup id
107 mkMatchGroup matches = MatchGroup matches placeHolderType
109 mkHsDictLet :: LHsBinds Id -> LHsExpr Id -> LHsExpr Id
110 -- Used for the dictionary bindings gotten from TcSimplify
111 -- We make them recursive to be on the safe side
112 mkHsDictLet binds expr
113 | isEmptyLHsBinds binds = expr
114 | otherwise = L (getLoc expr) (HsLet (HsValBinds val_binds) expr)
116 val_binds = ValBindsOut [(Recursive, binds)] []
118 mkHsConApp :: DataCon -> [Type] -> [HsExpr Id] -> LHsExpr Id
119 -- Used for constructing dictionary terms etc, so no locations
120 mkHsConApp data_con tys args
121 = foldl mk_app (nlHsTyApp (dataConWrapId data_con) tys) args
123 mk_app f a = noLoc (HsApp f (noLoc a))
125 mkSimpleHsAlt :: LPat id -> LHsExpr id -> LMatch id
126 -- A simple lambda with a single pattern, no binds, no guards; pre-typechecking
127 mkSimpleHsAlt pat expr
128 = mkSimpleMatch [pat] expr
130 -------------------------------
131 -- These are the bits of syntax that contain rebindable names
132 -- See RnEnv.lookupSyntaxName
134 mkHsIntegral i = HsIntegral i noSyntaxExpr
135 mkHsFractional f = HsFractional f noSyntaxExpr
136 mkHsIsString s = HsIsString s noSyntaxExpr
137 mkHsDo ctxt stmts body = HsDo ctxt stmts body placeHolderType
139 mkNPat lit neg = NPat lit neg noSyntaxExpr
140 mkNPlusKPat id lit = NPlusKPat id lit noSyntaxExpr noSyntaxExpr
142 mkTransformStmt stmts usingExpr = TransformStmt (stmts, []) usingExpr Nothing
143 mkTransformByStmt stmts usingExpr byExpr = TransformStmt (stmts, []) usingExpr (Just byExpr)
145 mkGroupUsingStmt stmts usingExpr = GroupStmt (stmts, []) (GroupByNothing usingExpr)
146 mkGroupByStmt stmts byExpr = GroupStmt (stmts, []) (GroupBySomething (Right noSyntaxExpr) byExpr)
147 mkGroupByUsingStmt stmts byExpr usingExpr = GroupStmt (stmts, []) (GroupBySomething (Left usingExpr) byExpr)
149 mkExprStmt expr = ExprStmt expr noSyntaxExpr placeHolderType
150 mkBindStmt pat expr = BindStmt pat expr noSyntaxExpr noSyntaxExpr
151 mkRecStmt stmts = RecStmt stmts [] [] [] emptyLHsBinds
153 -------------------------------
154 --- A useful function for building @OpApps@. The operator is always a
155 -- variable, and we don't know the fixity yet.
156 mkHsOpApp e1 op e2 = OpApp e1 (noLoc (HsVar op)) (error "mkOpApp:fixity") e2
158 mkHsSplice e = HsSplice unqualSplice e
160 unqualSplice = mkRdrUnqual (mkVarOccFS FSLIT("splice"))
161 -- A name (uniquified later) to
162 -- identify the splice
164 mkHsQuasiQuote quoter span quote = HsQuasiQuote unqualQuasiQuote quoter span quote
166 unqualQuasiQuote = mkRdrUnqual (mkVarOccFS FSLIT("quasiquote"))
167 -- A name (uniquified later) to
168 -- identify the quasi-quote
170 mkHsString s = HsString (mkFastString s)
173 userHsTyVarBndrs :: [Located name] -> [Located (HsTyVarBndr name)]
174 userHsTyVarBndrs bndrs = [ L loc (UserTyVar v) | L loc v <- bndrs ]
178 %************************************************************************
180 Constructing syntax with no location info
182 %************************************************************************
185 nlHsVar :: id -> LHsExpr id
186 nlHsVar n = noLoc (HsVar n)
188 nlHsLit :: HsLit -> LHsExpr id
189 nlHsLit n = noLoc (HsLit n)
191 nlVarPat :: id -> LPat id
192 nlVarPat n = noLoc (VarPat n)
194 nlLitPat :: HsLit -> LPat id
195 nlLitPat l = noLoc (LitPat l)
197 nlHsApp :: LHsExpr id -> LHsExpr id -> LHsExpr id
198 nlHsApp f x = noLoc (HsApp f x)
200 nlHsIntLit n = noLoc (HsLit (HsInt n))
202 nlHsApps :: id -> [LHsExpr id] -> LHsExpr id
203 nlHsApps f xs = foldl nlHsApp (nlHsVar f) xs
205 nlHsVarApps :: id -> [id] -> LHsExpr id
206 nlHsVarApps f xs = noLoc (foldl mk (HsVar f) (map HsVar xs))
208 mk f a = HsApp (noLoc f) (noLoc a)
210 nlConVarPat :: id -> [id] -> LPat id
211 nlConVarPat con vars = nlConPat con (map nlVarPat vars)
213 nlInfixConPat :: id -> LPat id -> LPat id -> LPat id
214 nlInfixConPat con l r = noLoc (ConPatIn (noLoc con) (InfixCon l r))
216 nlConPat :: id -> [LPat id] -> LPat id
217 nlConPat con pats = noLoc (ConPatIn (noLoc con) (PrefixCon pats))
219 nlNullaryConPat :: id -> LPat id
220 nlNullaryConPat con = noLoc (ConPatIn (noLoc con) (PrefixCon []))
222 nlWildConPat :: DataCon -> LPat RdrName
223 nlWildConPat con = noLoc (ConPatIn (noLoc (getRdrName con))
224 (PrefixCon (nOfThem (dataConSourceArity con) nlWildPat)))
226 nlTuplePat pats box = noLoc (TuplePat pats box placeHolderType)
227 nlWildPat = noLoc (WildPat placeHolderType) -- Pre-typechecking
229 nlHsDo :: HsStmtContext Name -> [LStmt id] -> LHsExpr id -> LHsExpr id
230 nlHsDo ctxt stmts body = noLoc (mkHsDo ctxt stmts body)
232 nlHsOpApp e1 op e2 = noLoc (mkHsOpApp e1 op e2)
234 nlHsLam match = noLoc (HsLam (mkMatchGroup [match]))
235 nlHsPar e = noLoc (HsPar e)
236 nlHsIf cond true false = noLoc (HsIf cond true false)
237 nlHsCase expr matches = noLoc (HsCase expr (mkMatchGroup matches))
238 nlTuple exprs box = noLoc (ExplicitTuple exprs box)
239 nlList exprs = noLoc (ExplicitList placeHolderType exprs)
241 nlHsAppTy f t = noLoc (HsAppTy f t)
242 nlHsTyVar x = noLoc (HsTyVar x)
243 nlHsFunTy a b = noLoc (HsFunTy a b)
245 nlHsTyConApp tycon tys = foldl nlHsAppTy (nlHsTyVar tycon) tys
250 %************************************************************************
252 Bindings; with a location at the top
254 %************************************************************************
257 mkFunBind :: Located id -> [LMatch id] -> HsBind id
258 -- Not infix, with place holders for coercion and free vars
259 mkFunBind fn ms = FunBind { fun_id = fn, fun_infix = False, fun_matches = mkMatchGroup ms,
260 fun_co_fn = idHsWrapper, bind_fvs = placeHolderNames,
264 mkVarBind :: SrcSpan -> id -> LHsExpr id -> LHsBind id
265 mkVarBind loc var rhs = mk_easy_FunBind loc var [] rhs
268 mk_easy_FunBind :: SrcSpan -> id -> [LPat id]
269 -> LHsExpr id -> LHsBind id
271 mk_easy_FunBind loc fun pats expr
272 = L loc $ mkFunBind (L loc fun) [mkMatch pats expr emptyLocalBinds]
275 mk_FunBind :: SrcSpan -> id
276 -> [([LPat id], LHsExpr id)]
279 mk_FunBind loc fun [] = panic "TcGenDeriv:mk_FunBind"
280 mk_FunBind loc fun pats_and_exprs
281 = L loc $ mkFunBind (L loc fun) matches
283 matches = [mkMatch p e emptyLocalBinds | (p,e) <-pats_and_exprs]
286 mkMatch :: [LPat id] -> LHsExpr id -> HsLocalBinds id -> LMatch id
287 mkMatch pats expr binds
288 = noLoc (Match (map paren pats) Nothing
289 (GRHSs (unguardedRHS expr) binds))
293 L l _ -> L l (ParPat p)
297 %************************************************************************
299 Collecting binders from HsBindGroups and HsBinds
301 %************************************************************************
303 Get all the binders in some HsBindGroups, IN THE ORDER OF APPEARANCE. eg.
311 it should return [x, y, f, a, b] (remember, order important).
314 collectLocalBinders :: HsLocalBindsLR idL idR -> [Located idL]
315 collectLocalBinders (HsValBinds val_binds) = collectHsValBinders val_binds
316 collectLocalBinders (HsIPBinds _) = []
317 collectLocalBinders EmptyLocalBinds = []
319 collectHsValBinders :: HsValBindsLR idL idR -> [Located idL]
320 collectHsValBinders (ValBindsIn binds sigs) = collectHsBindLocatedBinders binds
321 collectHsValBinders (ValBindsOut binds sigs) = foldr collect_one [] binds
323 collect_one (_,binds) acc = foldrBag (collectAcc . unLoc) acc binds
325 collectAcc :: HsBindLR idL idR -> [Located idL] -> [Located idL]
326 collectAcc (PatBind { pat_lhs = p }) acc = collectLocatedPatBinders p ++ acc
327 collectAcc (FunBind { fun_id = f }) acc = f : acc
328 collectAcc (VarBind { var_id = f }) acc = noLoc f : acc
329 collectAcc (AbsBinds { abs_exports = dbinds, abs_binds = binds }) acc
330 = [noLoc dp | (_,dp,_,_) <- dbinds] ++ acc
331 -- ++ foldr collectAcc acc binds
332 -- I don't think we want the binders from the nested binds
333 -- The only time we collect binders from a typechecked
334 -- binding (hence see AbsBinds) is in zonking in TcHsSyn
336 collectHsBindBinders :: LHsBindsLR idL idR -> [idL]
337 collectHsBindBinders binds = map unLoc (collectHsBindLocatedBinders binds)
339 collectHsBindLocatedBinders :: LHsBindsLR idL idR -> [Located idL]
340 collectHsBindLocatedBinders binds = foldrBag (collectAcc . unLoc) [] binds
344 %************************************************************************
346 Getting binders from statements
348 %************************************************************************
351 collectLStmtsBinders :: [LStmtLR idL idR] -> [Located idL]
352 collectLStmtsBinders = concatMap collectLStmtBinders
354 collectStmtsBinders :: [StmtLR idL idR] -> [Located idL]
355 collectStmtsBinders = concatMap collectStmtBinders
357 collectLStmtBinders :: LStmtLR idL idR -> [Located idL]
358 collectLStmtBinders = collectStmtBinders . unLoc
360 collectStmtBinders :: StmtLR idL idR -> [Located idL]
361 -- Id Binders for a Stmt... [but what about pattern-sig type vars]?
362 collectStmtBinders (BindStmt pat _ _ _) = collectLocatedPatBinders pat
363 collectStmtBinders (LetStmt binds) = collectLocalBinders binds
364 collectStmtBinders (ExprStmt _ _ _) = []
365 collectStmtBinders (ParStmt xs) = collectLStmtsBinders
367 collectStmtBinders (TransformStmt (stmts, _) _ _) = collectLStmtsBinders stmts
368 collectStmtBinders (GroupStmt (stmts, _) _) = collectLStmtsBinders stmts
369 collectStmtBinders (RecStmt ss _ _ _ _) = collectLStmtsBinders ss
373 %************************************************************************
375 %* Gathering stuff out of patterns
377 %************************************************************************
379 This function @collectPatBinders@ works with the ``collectBinders''
380 functions for @HsBinds@, etc. The order in which the binders are
381 collected is important; see @HsBinds.lhs@.
383 It collects the bounds *value* variables in renamed patterns; type variables
387 collectPatBinders :: LPat a -> [a]
388 collectPatBinders pat = map unLoc (collectLocatedPatBinders pat)
390 collectLocatedPatBinders :: LPat a -> [Located a]
391 collectLocatedPatBinders pat = collectl pat []
393 collectPatsBinders :: [LPat a] -> [a]
394 collectPatsBinders pats = map unLoc (collectLocatedPatsBinders pats)
396 collectLocatedPatsBinders :: [LPat a] -> [Located a]
397 collectLocatedPatsBinders pats = foldr collectl [] pats
399 ---------------------
400 collectl (L l pat) bndrs
403 go (VarPat var) = L l var : bndrs
404 go (VarPatOut var bs) = L l var : collectHsBindLocatedBinders bs
406 go (WildPat _) = bndrs
407 go (LazyPat pat) = collectl pat bndrs
408 go (BangPat pat) = collectl pat bndrs
409 go (AsPat a pat) = a : collectl pat bndrs
410 go (ViewPat exp pat _) = collectl pat bndrs
411 go (ParPat pat) = collectl pat bndrs
413 go (ListPat pats _) = foldr collectl bndrs pats
414 go (PArrPat pats _) = foldr collectl bndrs pats
415 go (TuplePat pats _ _) = foldr collectl bndrs pats
417 go (ConPatIn c ps) = foldr collectl bndrs (hsConPatArgs ps)
418 go (ConPatOut {pat_args=ps}) = foldr collectl bndrs (hsConPatArgs ps)
419 -- See Note [Dictionary binders in ConPatOut]
420 go (LitPat _) = bndrs
421 go (NPat _ _ _) = bndrs
422 go (NPlusKPat n _ _ _) = n : bndrs
424 go (SigPatIn pat _) = collectl pat bndrs
425 go (SigPatOut pat _) = collectl pat bndrs
426 go (QuasiQuotePat _) = bndrs
427 go (TypePat ty) = bndrs
428 go (CoPat _ pat ty) = collectl (noLoc pat) bndrs
431 Note [Dictionary binders in ConPatOut]
432 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
433 Do *not* gather (a) dictionary and (b) dictionary bindings as binders
434 of a ConPatOut pattern. For most calls it doesn't matter, because
435 it's pre-typechecker and there are no ConPatOuts. But it does matter
436 more in the desugarer; for example, DsUtils.mkSelectorBinds uses
437 collectPatBinders. In a lazy pattern, for example f ~(C x y) = ...,
438 we want to generate bindings for x,y but not for dictionaries bound by
439 C. (The type checker ensures they would not be used.)
441 Desugaring of arrow case expressions needs these bindings (see DsArrows
442 and arrowcase1), but SPJ (Jan 2007) says it's safer for it to use its
443 own pat-binder-collector:
445 Here's the problem. Consider
448 C :: Num a => a -> Int -> T a
450 f ~(C (n+1) m) = (n,m)
452 Here, the pattern (C (n+1)) binds a hidden dictionary (d::Num a),
453 and *also* uses that dictionary to match the (n+1) pattern. Yet, the
454 variables bound by the lazy pattern are n,m, *not* the dictionary d.
455 So in mkSelectorBinds in DsUtils, we want just m,n as the variables bound.
458 collectSigTysFromPats :: [InPat name] -> [LHsType name]
459 collectSigTysFromPats pats = foldr collect_lpat [] pats
461 collectSigTysFromPat :: InPat name -> [LHsType name]
462 collectSigTysFromPat pat = collect_lpat pat []
464 collect_lpat pat acc = collect_pat (unLoc pat) acc
466 collect_pat (SigPatIn pat ty) acc = collect_lpat pat (ty:acc)
467 collect_pat (TypePat ty) acc = ty:acc
469 collect_pat (LazyPat pat) acc = collect_lpat pat acc
470 collect_pat (BangPat pat) acc = collect_lpat pat acc
471 collect_pat (AsPat a pat) acc = collect_lpat pat acc
472 collect_pat (ParPat pat) acc = collect_lpat pat acc
473 collect_pat (ListPat pats _) acc = foldr collect_lpat acc pats
474 collect_pat (PArrPat pats _) acc = foldr collect_lpat acc pats
475 collect_pat (TuplePat pats _ _) acc = foldr collect_lpat acc pats
476 collect_pat (ConPatIn c ps) acc = foldr collect_lpat acc (hsConPatArgs ps)
477 collect_pat other acc = acc -- Literals, vars, wildcard