_not_a_home_module -> return False
-- | Looks up an identifier in the current interactive context (for :info)
+-- Filter the instances by the ones whose tycons (or clases resp)
+-- are in scope (qualified or otherwise). Otherwise we list a whole lot too many!
+-- The exact choice of which ones to show, and which to hide, is a judgement call.
+-- (see Trac #1581)
getInfo :: Session -> Name -> IO (Maybe (TyThing,Fixity,[Instance]))
-getInfo s name = withSession s $ \hsc_env -> tcRnGetInfo hsc_env name
+getInfo s name
+ = withSession s $ \hsc_env ->
+ do { mb_stuff <- tcRnGetInfo hsc_env name
+ ; case mb_stuff of
+ Nothing -> return Nothing
+ Just (thing, fixity, ispecs) -> do
+ { let rdr_env = ic_rn_gbl_env (hsc_IC hsc_env)
+ ; return (Just (thing, fixity, filter (plausible rdr_env) ispecs)) } }
+ where
+ plausible rdr_env ispec -- Dfun involving only names that are in ic_rn_glb_env
+ = all ok $ nameSetToList $ tyClsNamesOfType $ idType $ instanceDFunId ispec
+ where -- A name is ok if it's in the rdr_env,
+ -- whether qualified or not
+ ok n | n == name = True -- The one we looked for in the first place!
+ | isBuiltInSyntax n = True
+ | isExternalName n = any ((== n) . gre_name)
+ (lookupGRE_Name rdr_env n)
+ | otherwise = True
-- | Returns all names in scope in the current interactive context
getNamesInScope :: Session -> IO [Name]
-- in the home package all relevant modules are loaded.)
loadUnqualIfaces ictxt
- thing <- tcRnLookupName' name
+ thing <- tcRnLookupName' name
fixity <- lookupFixityRn name
- ispecs <- lookupInsts (icPrintUnqual ictxt) thing
+ ispecs <- lookupInsts thing
return (thing, fixity, ispecs)
-lookupInsts :: PrintUnqualified -> TyThing -> TcM [Instance]
--- Filter the instances by the ones whose tycons (or clases resp)
--- are in scope unqualified. Otherwise we list a whole lot too many!
-lookupInsts print_unqual (AClass cls)
+lookupInsts :: TyThing -> TcM [Instance]
+lookupInsts (AClass cls)
= do { inst_envs <- tcGetInstEnvs
- ; return [ ispec
- | ispec <- classInstances inst_envs cls
- , plausibleDFun print_unqual (instanceDFunId ispec) ] }
+ ; return (classInstances inst_envs cls) }
-lookupInsts print_unqual (ATyCon tc)
+lookupInsts (ATyCon tc)
= do { eps <- getEps -- Load all instances for all classes that are
-- in the type environment (which are all the ones
-- we've seen in any interface file so far)
; return [ ispec
| ispec <- instEnvElts home_ie ++ instEnvElts pkg_ie
, let dfun = instanceDFunId ispec
- , relevant dfun
- , plausibleDFun print_unqual dfun ] }
+ , relevant dfun ] }
where
relevant df = tc_name `elemNameSet` tyClsNamesOfDFunHead (idType df)
tc_name = tyConName tc
-lookupInsts print_unqual other = return []
-
-plausibleDFun print_unqual dfun -- Dfun involving only names that print unqualified
- = all ok (nameSetToList (tyClsNamesOfType (idType dfun)))
- where
- ok name | isBuiltInSyntax name = True
- | isExternalName name =
- isNothing $ fst print_unqual (nameModule name)
- (nameOccName name)
- | otherwise = True
+lookupInsts other = return []
loadUnqualIfaces :: InteractiveContext -> TcM ()
-- Load the home module for everything that is in scope unqualified
will be printed. If <replaceable>name</replaceable> has
been loaded from a source file, then GHCi will also display
the location of its definition in the source.</para>
+ <para>For types and classes, GHCi also summarises instances that
+ mention them. To avoid showing irrelevant information, an instance
+ is shown only if (a) its head mentions <relaceable>name</replaceable>,
+ and (b) all the other things mentioned in the instance
+ are in scope (either qualified or otherwise) as a result of
+ a <literal>:load</literal> or <literal>:module</literal> commands. </para>
</listitem>
</varlistentry>