2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
4 \section[DsMonad]{@DsMonad@: monadery used in desugaring}
9 initDs, returnDs, thenDs, andDs, mapDs, listDs,
10 mapAndUnzipDs, zipWithDs, foldlDs,
12 newTyVarsDs, cloneTyVarsDs,
13 duplicateLocalDs, newSysLocalDs, newSysLocalsDs,
15 getSrcLocDs, putSrcLocDs,
16 getModuleAndGroupDs, getUniqueDs,
17 extendEnvDs, lookupEnvDs,
22 DsMatchContext(..), DsMatchKind(..), pprDsWarnings
25 #include "HsVersions.h"
27 import Bag ( emptyBag, snocBag, bagToList, Bag )
28 import BasicTypes ( Module )
29 import ErrUtils ( WarnMsg )
30 import HsSyn ( OutPat )
31 import MkId ( mkSysLocal )
32 import Id ( mkIdWithNewUniq,
33 lookupIdEnv, growIdEnvList, IdEnv, Id
36 import SrcLoc ( noSrcLoc, SrcLoc )
37 import TcHsSyn ( TypecheckedPat )
39 import TyVar ( cloneTyVar, TyVar )
40 import UniqSupply ( splitUniqSupply, getUnique, getUniques,
42 import Unique ( Unique )
43 import Util ( zipWithEqual, panic )
48 Now the mondo monad magic (yes, @DsM@ is a silly name)---carry around
49 a @UniqueSupply@ and some annotations, which
50 presumably include source-file location information:
54 -> SrcLoc -- to put in pattern-matching error msgs
55 -> (Module, Group) -- module + group name : for SCC profiling
58 -> (result, DsWarnings)
60 type DsWarnings = Bag WarnMsg -- The desugarer reports matches which are
61 -- completely shadowed or incomplete patterns
63 type Group = FAST_STRING
67 {-# INLINE returnDs #-}
69 -- initDs returns the UniqSupply out the end (not just the result)
73 -> (Module, Group) -- module name: for profiling; (group name: from switches)
77 initDs init_us env module_and_group action
78 = action init_us noSrcLoc module_and_group env emptyBag
80 thenDs :: DsM a -> (a -> DsM b) -> DsM b
81 andDs :: (a -> a -> a) -> DsM a -> DsM a -> DsM a
83 thenDs m1 m2 us loc mod_and_grp env warns
84 = case splitUniqSupply us of { (s1, s2) ->
85 case (m1 s1 loc mod_and_grp env warns) of { (result, warns1) ->
86 m2 result s2 loc mod_and_grp env warns1}}
88 andDs combiner m1 m2 us loc mod_and_grp env warns
89 = case splitUniqSupply us of { (s1, s2) ->
90 case (m1 s1 loc mod_and_grp env warns) of { (result1, warns1) ->
91 case (m2 s2 loc mod_and_grp env warns1) of { (result2, warns2) ->
92 (combiner result1 result2, warns2) }}}
94 returnDs :: a -> DsM a
95 returnDs result us loc mod_and_grp env warns = (result, warns)
97 listDs :: [DsM a] -> DsM [a]
98 listDs [] = returnDs []
101 listDs xs `thenDs` \ rs ->
104 mapDs :: (a -> DsM b) -> [a] -> DsM [b]
106 mapDs f [] = returnDs []
108 = f x `thenDs` \ r ->
109 mapDs f xs `thenDs` \ rs ->
112 foldlDs :: (a -> b -> DsM a) -> a -> [b] -> DsM a
114 foldlDs k z [] = returnDs z
115 foldlDs k z (x:xs) = k z x `thenDs` \ r ->
119 mapAndUnzipDs :: (a -> DsM (b, c)) -> [a] -> DsM ([b], [c])
121 mapAndUnzipDs f [] = returnDs ([], [])
122 mapAndUnzipDs f (x:xs)
123 = f x `thenDs` \ (r1, r2) ->
124 mapAndUnzipDs f xs `thenDs` \ (rs1, rs2) ->
125 returnDs (r1:rs1, r2:rs2)
127 zipWithDs :: (a -> b -> DsM c) -> [a] -> [b] -> DsM [c]
129 zipWithDs f [] ys = returnDs []
130 zipWithDs f (x:xs) (y:ys)
131 = f x y `thenDs` \ r ->
132 zipWithDs f xs ys `thenDs` \ rs ->
136 And all this mysterious stuff is so we can occasionally reach out and
137 grab one or more names. @newLocalDs@ isn't exported---exported
138 functions are defined with it. The difference in name-strings makes
139 it easier to read debugging output.
142 newLocalDs :: FAST_STRING -> Type -> DsM Id
143 newLocalDs nm ty us loc mod_and_grp env warns
144 = case (getUnique us) of { assigned_uniq ->
145 (mkSysLocal nm assigned_uniq ty loc, warns) }
147 newSysLocalDs = newLocalDs SLIT("ds")
148 newSysLocalsDs tys = mapDs (newLocalDs SLIT("ds")) tys
149 newFailLocalDs = newLocalDs SLIT("fail")
151 getUniqueDs :: DsM Unique
152 getUniqueDs us loc mod_and_grp env warns
153 = case (getUnique us) of { assigned_uniq ->
154 (assigned_uniq, warns) }
156 duplicateLocalDs :: Id -> DsM Id
157 duplicateLocalDs old_local us loc mod_and_grp env warns
158 = case (getUnique us) of { assigned_uniq ->
159 (mkIdWithNewUniq old_local assigned_uniq, warns) }
161 cloneTyVarsDs :: [TyVar] -> DsM [TyVar]
162 cloneTyVarsDs tyvars us loc mod_and_grp env warns
163 = case (getUniques (length tyvars) us) of { uniqs ->
164 (zipWithEqual "cloneTyVarsDs" cloneTyVar tyvars uniqs, warns) }
168 newTyVarsDs :: [TyVar] -> DsM [TyVar]
170 newTyVarsDs tyvar_tmpls us loc mod_and_grp env warns
171 = case (getUniques (length tyvar_tmpls) us) of { uniqs ->
172 (zipWithEqual "newTyVarsDs" cloneTyVar tyvar_tmpls uniqs, warns) }
175 We can also reach out and either set/grab location information from
176 the @SrcLoc@ being carried around.
178 uniqSMtoDsM :: UniqSM a -> DsM a
180 uniqSMtoDsM u_action us loc mod_and_grp env warns
181 = (u_action us, warns)
183 getSrcLocDs :: DsM SrcLoc
184 getSrcLocDs us loc mod_and_grp env warns
187 putSrcLocDs :: SrcLoc -> DsM a -> DsM a
188 putSrcLocDs new_loc expr us old_loc mod_and_grp env warns
189 = expr us new_loc mod_and_grp env warns
191 dsWarn :: WarnMsg -> DsM ()
192 dsWarn warn us loc mod_and_grp env warns = ((), warns `snocBag` warn)
197 getModuleAndGroupDs :: DsM (FAST_STRING, FAST_STRING)
198 getModuleAndGroupDs us loc mod_and_grp env warns
199 = (mod_and_grp, warns)
203 type DsIdEnv = IdEnv Id
205 extendEnvDs :: [(Id, Id)] -> DsM a -> DsM a
207 extendEnvDs pairs then_do us loc mod_and_grp old_env warns
208 = then_do us loc mod_and_grp (growIdEnvList old_env pairs) warns
210 lookupEnvDs :: Id -> DsM Id
211 lookupEnvDs id us loc mod_and_grp env warns
212 = (case (lookupIdEnv env id) of
218 %************************************************************************
220 %* type synonym EquationInfo and access functions for its pieces *
222 %************************************************************************
226 = DsMatchContext DsMatchKind [TypecheckedPat] SrcLoc
240 pprDsWarnings :: DsWarnings -> SDoc
241 pprDsWarnings warns = vcat (bagToList warns)