1 -----------------------------------------------------------------------------
3 -- GHCi Interactive debugging commands
5 -- Pepe Iborra (supported by Google SoC) 2006
7 -- ToDo: lots of violation of layering here. This module should
8 -- decide whether it is above the GHC API (import GHC and nothing
11 -----------------------------------------------------------------------------
13 module Debugger (pprintClosureCommand, showTerm) where
16 import RtClosureInspect
22 import Var hiding ( varName )
28 import InteractiveEval
30 import Pretty ( Mode(..), showDocWith )
33 import Control.Exception
42 #include "HsVersions.h"
43 -------------------------------------
44 -- | The :print & friends commands
45 -------------------------------------
46 pprintClosureCommand :: Session -> Bool -> Bool -> String -> IO ()
47 pprintClosureCommand session bindThings force str = do
48 tythings <- (catMaybes . concat) `liftM`
49 mapM (\w -> GHC.parseName session w >>=
50 mapM (GHC.lookupName session))
52 let ids = [id | AnId id <- tythings]
54 -- Obtain the terms and the recovered type information
55 (terms, substs) <- unzip `liftM` mapM (go session) ids
57 -- Apply the substitutions obtained after recovering the types
58 modifySession session $ \hsc_env ->
59 hsc_env{hsc_IC = foldr (flip substInteractiveContext)
61 (map skolemiseSubst substs)}
62 -- Finally, print the Terms
63 unqual <- GHC.getPrintUnqual session
64 let showSDocForUserOneLine unqual doc =
65 showDocWith LeftMode (doc (mkErrStyle unqual))
66 docterms <- mapM (showTerm session) terms
67 (putStrLn . showSDocForUserOneLine unqual . vcat)
68 (zipWith (\id docterm -> ppr id <+> char '=' <+> docterm)
73 -- Do the obtainTerm--bindSuspensions-computeSubstitution dance
74 go :: Session -> Id -> IO (Term, TvSubst)
76 term_ <- GHC.obtainTerm cms force id
77 term <- tidyTermTyVars cms term_
78 term' <- if not bindThings then return term
79 else bindSuspensions cms term
80 -- Before leaving, we compare the type obtained to see if it's more specific
81 -- Then, we extract a substitution,
82 -- mapping the old tyvars to the reconstructed types.
83 let Just reconstructed_type = termType term
84 Just subst = computeRTTIsubst (idType id) (reconstructed_type)
87 tidyTermTyVars :: Session -> Term -> IO Term
88 tidyTermTyVars (Session ref) t = do
89 hsc_env <- readIORef ref
90 let env_tvs = ic_tyvars (hsc_IC hsc_env)
92 tvs = env_tvs `minusVarSet` my_tvs
93 tyvarOccName = nameOccName . tyVarName
94 tidyEnv = (initTidyOccEnv (map tyvarOccName (varSetElems tvs))
95 , env_tvs `intersectVarSet` my_tvs)
96 return$ mapTermType (snd . tidyOpenType tidyEnv) t
98 -- | Give names, and bind in the interactive environment, to all the suspensions
99 -- included (inductively) in a term
100 bindSuspensions :: Session -> Term -> IO Term
101 bindSuspensions cms@(Session ref) t = do
102 hsc_env <- readIORef ref
103 inScope <- GHC.getBindings cms
104 let ictxt = hsc_IC hsc_env
106 alreadyUsedNames = map (occNameString . nameOccName . getName) inScope
107 availNames = map ((prefix++) . show) [1..] \\ alreadyUsedNames
108 availNames_var <- newIORef availNames
109 (t', stuff) <- foldTerm (nameSuspensionsAndGetInfos availNames_var) t
110 let (names, tys, hvals) = unzip3 stuff
111 let tys' = map (fst.skolemiseTy) tys
112 let ids = [ mkGlobalId VanillaGlobal name ty vanillaIdInfo
113 | (name,ty) <- zip names tys']
114 new_tyvars = tyVarsOfTypes tys'
115 new_ic = extendInteractiveContext ictxt ids new_tyvars
116 extendLinkEnv (zip names hvals)
117 writeIORef ref (hsc_env {hsc_IC = new_ic })
121 -- Processing suspensions. Give names and recopilate info
122 nameSuspensionsAndGetInfos :: IORef [String] ->
123 TermFold (IO (Term, [(Name,Type,HValue)]))
124 nameSuspensionsAndGetInfos freeNames = TermFold
126 fSuspension = doSuspension freeNames
127 , fTerm = \ty dc v tt -> do
129 let (terms,names) = unzip tt'
130 return (Term ty dc v terms, concat names)
131 , fPrim = \ty n ->return (Prim ty n,[])
133 doSuspension freeNames ct mb_ty hval Nothing = do
134 name <- atomicModifyIORef freeNames (\x->(tail x, head x))
135 n <- newGrimName cms name
136 let ty' = fromMaybe (error "unexpected") mb_ty
137 return (Suspension ct mb_ty hval (Just n), [(n,ty',hval)])
140 -- A custom Term printer to enable the use of Show instances
141 showTerm cms@(Session ref) = cPprTerm cPpr
143 cPpr = \p-> cPprShowable : cPprTermBase p
144 cPprShowable prec t@Term{ty=ty, dc=dc, val=val} =
145 if not (isFullyEvaluatedTerm t)
148 hsc_env <- readIORef ref
149 dflags <- GHC.getSessionDynFlags cms
151 (new_env, bname) <- bindToFreshName hsc_env ty "showme"
152 writeIORef ref (new_env)
153 let noop_log _ _ _ _ = return ()
154 expr = "show " ++ showSDoc (ppr bname)
155 GHC.setSessionDynFlags cms dflags{log_action=noop_log}
156 mb_txt <- withExtendedLinkEnv [(bname, val)]
157 (GHC.compileExpr cms expr)
158 let myprec = 10 -- application precedence. TODO Infix constructors
160 Just txt_ | txt <- unsafeCoerce# txt_, not (null txt)
161 -> return $ Just$ cparen (prec >= myprec &&
166 writeIORef ref hsc_env
167 GHC.setSessionDynFlags cms dflags
168 needsParens ('"':txt) = False -- some simple heuristics to see whether parens
169 -- are redundant in an arbitrary Show output
170 needsParens ('(':txt) = False
171 needsParens txt = ' ' `elem` txt
174 bindToFreshName hsc_env ty userName = do
175 name <- newGrimName cms userName
176 let ictxt = hsc_IC hsc_env
177 tmp_ids = ic_tmp_ids ictxt
178 id = mkGlobalId VanillaGlobal name (sigmaType ty) vanillaIdInfo
179 new_ic = ictxt { ic_tmp_ids = id : tmp_ids }
180 return (hsc_env {hsc_IC = new_ic }, name)
182 -- Create new uniques and give them sequentially numbered names
183 -- newGrimName :: Session -> String -> IO Name
184 newGrimName cms userName = do
185 us <- mkSplitUniqSupply 'b'
186 let unique = uniqFromSupply us
187 occname = mkOccName varName userName
188 name = mkInternalName unique occname noSrcSpan