they may be affected by renaming (which isn't fully worked out yet).
\begin{code}
-#include "HsVersions.h"
-
module RnBinds (
rnTopBinds, rnTopMonoBinds,
- rnMethodBinds,
+ rnMethodBinds, renameSigs,
rnBinds, rnMonoBinds
) where
-IMP_Ubiq()
-IMPORT_DELOOPER(RnLoop) -- break the RnPass/RnExpr/RnBinds loops
+#include "HsVersions.h"
+
+import {-# SOURCE #-} RnSource ( rnHsSigType )
import HsSyn
-import HsPragmas ( isNoGenPragmas, noGenPragmas )
+import HsBinds ( sigsForMe )
import RdrHsSyn
import RnHsSyn
import RnMonad
import RnExpr ( rnMatch, rnGRHSsAndBinds, rnPat, checkPrecMatch )
-import RnEnv ( bindLocatedLocalsRn, lookupRn, lookupOccRn, isUnboundName )
-
+import RnEnv ( bindLocatedLocalsRn, lookupBndrRn, lookupOccRn, lookupGlobalOccRn,
+ newLocalNames, isUnboundName, warnUnusedBinds
+ )
import CmdLineOpts ( opt_SigsRequired )
-import Digraph ( stronglyConnComp )
-import ErrUtils ( addErrLoc, addShortErrLocLine )
+import Digraph ( stronglyConnComp, SCC(..) )
import Name ( OccName(..), Provenance,
- Name {- instance Eq -},
- NameSet(..), emptyNameSet, mkNameSet, unionNameSets,
+ Name, isExportedName,
+ NameSet, emptyNameSet, mkNameSet, unionNameSets,
minusNameSet, unionManyNameSets, elemNameSet, unitNameSet, nameSetToList
)
-import Maybes ( catMaybes )
---import PprStyle--ToDo:rm
-import Pretty
-import Util ( thenCmp, isIn, removeDups, panic, panic#, assertPanic )
-import UniqSet ( SYN_IE(UniqSet) )
+import BasicTypes ( RecFlag(..), TopLevelFlag(..) )
+import Util ( thenCmp, removeDups, panic, panic#, assertPanic )
+import UniqSet ( UniqSet )
import ListSetOps ( minusList )
import Bag ( bagToList )
import UniqFM ( UniqFM )
-import ErrUtils ( SYN_IE(Error) )
+import Outputable
\end{code}
-- ToDo: Put the annotations into the monad, so that they arrive in the proper
rnTopBinds :: RdrNameHsBinds -> RnMS s RenamedHsBinds
rnTopBinds EmptyBinds = returnRn EmptyBinds
-rnTopBinds (SingleBind (RecBind bind)) = rnTopMonoBinds bind []
-rnTopBinds (BindWith (RecBind bind) sigs) = rnTopMonoBinds bind sigs
+rnTopBinds (MonoBind bind sigs _) = rnTopMonoBinds bind sigs
-- The parser doesn't produce other forms
= returnRn EmptyBinds
rnTopMonoBinds mbinds sigs
- = mapRn lookupRn binder_rdr_names `thenRn` \ binder_names ->
+ = mapRn lookupBndrRn binder_rdr_names `thenRn` \ binder_names ->
let
- binder_set = mkNameSet binder_names
+ binder_set = mkNameSet binder_names
+ exported_binders = mkNameSet (filter isExportedName binder_names)
in
- rn_mono_binds True {- top level -}
+ rn_mono_binds TopLevel
binder_set mbinds sigs `thenRn` \ (new_binds, fv_set) ->
+ let
+ unused_binders = binder_set `minusNameSet` (fv_set `unionNameSets` exported_binders)
+ in
+ warnUnusedBinds unused_binders `thenRn_`
returnRn new_binds
where
binder_rdr_names = map fst (bagToList (collectMonoBinders mbinds))
-> (RenamedHsBinds -> RnMS s (result, FreeVars))
-> RnMS s (result, FreeVars)
-rnBinds EmptyBinds thing_inside = thing_inside EmptyBinds
-rnBinds (SingleBind (RecBind bind)) thing_inside = rnMonoBinds bind [] thing_inside
-rnBinds (BindWith (RecBind bind) sigs) thing_inside = rnMonoBinds bind sigs thing_inside
+rnBinds EmptyBinds thing_inside = thing_inside EmptyBinds
+rnBinds (MonoBind bind sigs _) thing_inside = rnMonoBinds bind sigs thing_inside
-- the parser doesn't produce other forms
= -- Extract all the binders in this group,
-- and extend current scope, inventing new names for the new binders
-- This also checks that the names form a set
- bindLocatedLocalsRn "binding group" mbinders_w_srclocs $ \ new_mbinders ->
+ bindLocatedLocalsRn (text "binding group") mbinders_w_srclocs $ \ new_mbinders ->
let
binder_set = mkNameSet new_mbinders
in
- rn_mono_binds False {- not top level -}
+ rn_mono_binds NotTopLevel
binder_set mbinds sigs `thenRn` \ (binds,bind_fvs) ->
-- Now do the "thing inside", and deal with the free-variable calculations
thing_inside binds `thenRn` \ (result,result_fvs) ->
- returnRn (result, (result_fvs `unionNameSets` bind_fvs) `minusNameSet` binder_set)
+ let
+ all_fvs = result_fvs `unionNameSets` bind_fvs
+ net_fvs = all_fvs `minusNameSet` binder_set
+ unused_binders = binder_set `minusNameSet` all_fvs
+ in
+ warnUnusedBinds unused_binders `thenRn_`
+ returnRn (result, net_fvs)
where
mbinders_w_srclocs = bagToList (collectMonoBinders mbinds)
\end{code}
@rnNestedMonoBinds@ (for the nested ones).
\begin{code}
-rn_mono_binds :: Bool -- True <=> top level
+rn_mono_binds :: TopLevelFlag
-> NameSet -- Binders of this group
-> RdrNameMonoBinds
-> [RdrNameSig] -- Signatures attached to this group
-> RnMS s (RenamedHsBinds, --
FreeVars) -- Free variables
-rn_mono_binds is_top_lev binders mbinds sigs
+rn_mono_binds top_lev binders mbinds sigs
=
-- Rename the bindings, returning a MonoBindsInfo
-- which is a list of indivisible vertices so far as
-- the strongly-connected-components (SCC) analysis is concerned
- rnBindSigs is_top_lev binders sigs `thenRn` \ siglist ->
- flattenMonoBinds 0 siglist mbinds `thenRn` \ (_, mbinds_info) ->
+ renameSigs top_lev False binders sigs `thenRn` \ siglist ->
+ flattenMonoBinds siglist mbinds `thenRn` \ mbinds_info ->
-- Do the SCC analysis
- let vertices = mkVertices mbinds_info
- edges = mkEdges mbinds_info
- scc_result = stronglyConnComp (==) edges vertices
- final_binds = foldr1 ThenBinds (map (reconstructCycle edges mbinds_info) scc_result)
+ let edges = mkEdges (mbinds_info `zip` [(0::Int)..])
+ scc_result = stronglyConnComp edges
+ final_binds = foldr1 ThenBinds (map reconstructCycle scc_result)
-- Deal with bound and free-var calculation
- rhs_fvs = unionManyNameSets [fvs | (_,_,fvs,_,_) <- mbinds_info]
+ rhs_fvs = unionManyNameSets [fvs | (_,fvs,_,_) <- mbinds_info]
in
returnRn (final_binds, rhs_fvs)
\end{code}
unique ``vertex tags'' on its output; minor plumbing required.
\begin{code}
-flattenMonoBinds :: Int -- Next free vertex tag
- -> [RenamedSig] -- Signatures
+flattenMonoBinds :: [RenamedSig] -- Signatures
-> RdrNameMonoBinds
- -> RnMS s (Int, FlatMonoBindsInfo)
+ -> RnMS s [FlatMonoBindsInfo]
-flattenMonoBinds uniq sigs EmptyMonoBinds = returnRn (uniq, [])
+flattenMonoBinds sigs EmptyMonoBinds = returnRn []
-flattenMonoBinds uniq sigs (AndMonoBinds bs1 bs2)
- = flattenMonoBinds uniq sigs bs1 `thenRn` \ (uniq1, flat1) ->
- flattenMonoBinds uniq1 sigs bs2 `thenRn` \ (uniq2, flat2) ->
- returnRn (uniq2, flat1 ++ flat2)
+flattenMonoBinds sigs (AndMonoBinds bs1 bs2)
+ = flattenMonoBinds sigs bs1 `thenRn` \ flat1 ->
+ flattenMonoBinds sigs bs2 `thenRn` \ flat2 ->
+ returnRn (flat1 ++ flat2)
-flattenMonoBinds uniq sigs (PatMonoBind pat grhss_and_binds locn)
+flattenMonoBinds sigs (PatMonoBind pat grhss_and_binds locn)
= pushSrcLocRn locn $
rnPat pat `thenRn` \ pat' ->
rnGRHSsAndBinds grhss_and_binds `thenRn` \ (grhss_and_binds', fvs) ->
-- Find which things are bound in this group
let
names_bound_here = mkNameSet (collectPatBinders pat')
- sigs_for_me = filter ((`elemNameSet` names_bound_here) . sig_name) sigs
+ sigs_for_me = sigsForMe (`elemNameSet` names_bound_here) sigs
sigs_fvs = foldr sig_fv emptyNameSet sigs_for_me
in
- returnRn (
- uniq + 1,
- [(uniq,
- names_bound_here,
+ returnRn
+ [(names_bound_here,
fvs `unionNameSets` sigs_fvs,
PatMonoBind pat' grhss_and_binds' locn,
sigs_for_me
)]
- )
-flattenMonoBinds uniq sigs (FunMonoBind name inf matches locn)
+flattenMonoBinds sigs (FunMonoBind name inf matches locn)
= pushSrcLocRn locn $
mapRn (checkPrecMatch inf name) matches `thenRn_`
- lookupRn name `thenRn` \ name' ->
+ lookupBndrRn name `thenRn` \ name' ->
mapAndUnzipRn rnMatch matches `thenRn` \ (new_matches, fv_lists) ->
let
fvs = unionManyNameSets fv_lists
- sigs_for_me = filter ((name' ==) . sig_name) sigs
+ sigs_for_me = sigsForMe (name' ==) sigs
sigs_fvs = foldr sig_fv emptyNameSet sigs_for_me
in
- returnRn (
- uniq + 1,
- [(uniq,
- unitNameSet name',
+ returnRn
+ [(unitNameSet name',
fvs `unionNameSets` sigs_fvs,
FunMonoBind name' inf new_matches locn,
sigs_for_me
)]
- )
\end{code}
= andRn AndMonoBinds (rnMethodBinds mb1)
(rnMethodBinds mb2)
-rnMethodBinds (FunMonoBind occname inf matches locn)
+rnMethodBinds (FunMonoBind name inf matches locn)
= pushSrcLocRn locn $
- mapRn (checkPrecMatch inf occname) matches `thenRn_`
- lookupRn occname `thenRn` \ op_name ->
+ mapRn (checkPrecMatch inf name) matches `thenRn_`
+
+ lookupGlobalOccRn name `thenRn` \ sel_name ->
+ -- We use the selector name as the binder
+
mapAndUnzipRn rnMatch matches `thenRn` \ (new_matches, _) ->
- returnRn (FunMonoBind op_name inf new_matches locn)
+ returnRn (FunMonoBind sel_name inf new_matches locn)
-rnMethodBinds (PatMonoBind (VarPatIn occname) grhss_and_binds locn)
+rnMethodBinds (PatMonoBind (VarPatIn name) grhss_and_binds locn)
= pushSrcLocRn locn $
- lookupRn occname `thenRn` \ op_name ->
+ lookupGlobalOccRn name `thenRn` \ sel_name ->
rnGRHSsAndBinds grhss_and_binds `thenRn` \ (grhss_and_binds', _) ->
- returnRn (PatMonoBind (VarPatIn op_name) grhss_and_binds' locn)
+ returnRn (PatMonoBind (VarPatIn sel_name) grhss_and_binds' locn)
-- Can't handle method pattern-bindings which bind multiple methods.
rnMethodBinds mbind@(PatMonoBind other_pat _ locn)
as the two cases are similar.
\begin{code}
-reconstructCycle :: [Edge] -- Original edges
- -> FlatMonoBindsInfo
- -> Cycle
+reconstructCycle :: SCC FlatMonoBindsInfo
-> RenamedHsBinds
-reconstructCycle edges mbi cycle
- = mk_binds this_gp_binds this_gp_sigs (isCyclic edges cycle)
+reconstructCycle (AcyclicSCC (_, _, binds, sigs))
+ = MonoBind binds sigs NonRecursive
+
+reconstructCycle (CyclicSCC cycle)
+ = MonoBind this_gp_binds this_gp_sigs Recursive
where
- relevant_binds_and_sigs = [(binds,sigs) | (vertex, _, _, binds, sigs) <- mbi,
- vertex `is_elem` cycle]
- (binds, sig_lists) = unzip relevant_binds_and_sigs
- this_gp_binds = foldr1 AndMonoBinds binds
- this_gp_sigs = foldr1 (++) sig_lists
-
- is_elem = isIn "reconstructRec"
-
- mk_binds :: RenamedMonoBinds -> [RenamedSig] -> Bool -> RenamedHsBinds
- mk_binds bs [] True = SingleBind (RecBind bs)
- mk_binds bs ss True = BindWith (RecBind bs) ss
- mk_binds bs [] False = SingleBind (NonRecBind bs)
- mk_binds bs ss False = BindWith (NonRecBind bs) ss
-
- -- moved from Digraph, as this is the only use here
- -- (avoid overloading cost). We have to use elem
- -- (not FiniteMaps or whatever), because there may be
- -- many edges out of one vertex. We give it its own
- -- "elem" just for speed.
-
- isCyclic es [] = panic "isCyclic: empty component"
- isCyclic es [v] = (v,v) `elem` es
- isCyclic es vs = True
-
- elem _ [] = False
- elem x (y:ys) = x==y || elem x ys
+ this_gp_binds = foldr1 AndMonoBinds [binds | (_, _, binds, _) <- cycle]
+ this_gp_sigs = foldr1 (++) [sigs | (_, _, _, sigs) <- cycle]
\end{code}
%************************************************************************
\begin{code}
type FlatMonoBindsInfo
- = [(VertexTag, -- Identifies the vertex
- NameSet, -- Set of names defined in this vertex
- NameSet, -- Set of names used in this vertex
- RenamedMonoBinds, -- Binding for this vertex (always just one binding, either fun or pat)
- [RenamedSig]) -- Signatures, if any, for this vertex
- ]
-
-mkVertices :: FlatMonoBindsInfo -> [VertexTag]
-mkEdges :: FlatMonoBindsInfo -> [Edge]
+ = (NameSet, -- Set of names defined in this vertex
+ NameSet, -- Set of names used in this vertex
+ RenamedMonoBinds,
+ [RenamedSig]) -- Signatures, if any, for this vertex
-mkVertices info = [ vertex | (vertex,_,_,_,_) <- info]
+mkEdges :: [(FlatMonoBindsInfo, VertexTag)] -> [(FlatMonoBindsInfo, VertexTag, [VertexTag])]
-mkEdges flat_info -- An edge (v,v') indicates that v depends on v'
- = [ (source_vertex, target_vertex)
- | (source_vertex, _, used_names, _, _) <- flat_info,
- target_name <- nameSetToList used_names,
- target_vertex <- vertices_defining target_name flat_info
+mkEdges flat_info
+ = [ (info, tag, dest_vertices (nameSetToList names_used))
+ | (info@(names_defined, names_used, mbind, sigs), tag) <- flat_info
]
- where
- -- If each name only has one binding in this group, then
- -- vertices_defining will always return the empty list, or a
- -- singleton. The case when there is more than one binding (an
- -- error) needs more thought.
-
- vertices_defining name flat_info2
- = [ vertex | (vertex, names_defined, _, _, _) <- flat_info2,
- name `elemNameSet` names_defined
- ]
+ where
+ -- An edge (v,v') indicates that v depends on v'
+ dest_vertices src_mentions = [ target_vertex
+ | ((names_defined, _, _, _), target_vertex) <- flat_info,
+ mentioned_name <- src_mentions,
+ mentioned_name `elemNameSet` names_defined
+ ]
\end{code}
%* *
%************************************************************************
-@rnBindSigs@ checks for: (a)~more than one sig for one thing;
+@renameSigs@ checks for: (a)~more than one sig for one thing;
(b)~signatures given for things not bound here; (c)~with suitably
flaggery, that all top-level things have type signatures.
\begin{code}
-rnBindSigs :: Bool -- True <=> top-level binders
+renameSigs :: TopLevelFlag
+ -> Bool -- True <-> sigs for an instance decl
+ -- hence SPECIALISE instance prags ok
-> NameSet -- Set of names bound in this group
-> [RdrNameSig]
-> RnMS s [RenamedSig] -- List of Sig constructors
-rnBindSigs is_toplev binders sigs
+renameSigs top_lev inst_decl binders sigs
= -- Rename the signatures
mapRn renameSig sigs `thenRn` \ sigs' ->
-- (b) signatures for things not in this group
-- (c) optionally, bindings with no signature
let
- (goodies, dups) = removeDups cmp_sig (filter (not.isUnboundName.sig_name) sigs')
- not_this_group = filter (\sig -> not (sig_name sig `elemNameSet` binders)) goodies
+ (goodies, dups) = removeDups cmp_sig (sigsForMe (not . isUnboundName) sigs')
+ not_this_group = sigsForMe (not . (`elemNameSet` binders)) goodies
+ spec_inst_sigs = [s | s@(SpecInstSig _ _) <- goodies]
type_sig_vars = [n | Sig n _ _ <- goodies]
- un_sigd_binders
- | is_toplev && opt_SigsRequired = nameSetToList binders `minusList` type_sig_vars
- | otherwise = []
+ sigs_required = case top_lev of {TopLevel -> opt_SigsRequired; NotTopLevel -> False}
+ un_sigd_binders | sigs_required = nameSetToList binders `minusList` type_sig_vars
+ | otherwise = []
in
mapRn dupSigDeclErr dups `thenRn_`
mapRn unknownSigErr not_this_group `thenRn_`
+ (if not inst_decl then
+ mapRn unknownSigErr spec_inst_sigs
+ else
+ returnRn []
+ ) `thenRn_`
mapRn (addErrRn.missingSigErr) un_sigd_binders `thenRn_`
returnRn sigs' -- bad ones and all:
renameSig (Sig v ty src_loc)
= pushSrcLocRn src_loc $
- lookupRn v `thenRn` \ new_v ->
- rnHsType ty `thenRn` \ new_ty ->
+ lookupBndrRn v `thenRn` \ new_v ->
+ rnHsSigType (quotes (ppr v)) ty `thenRn` \ new_ty ->
returnRn (Sig new_v new_ty src_loc)
+renameSig (SpecInstSig ty src_loc)
+ = pushSrcLocRn src_loc $
+ rnHsSigType (text "A SPECIALISE instance pragma") ty `thenRn` \ new_ty ->
+ returnRn (SpecInstSig new_ty src_loc)
+
renameSig (SpecSig v ty using src_loc)
= pushSrcLocRn src_loc $
- lookupRn v `thenRn` \ new_v ->
- rnHsType ty `thenRn` \ new_ty ->
- rn_using using `thenRn` \ new_using ->
+ lookupBndrRn v `thenRn` \ new_v ->
+ rnHsSigType (quotes (ppr v)) ty `thenRn` \ new_ty ->
+ rn_using using `thenRn` \ new_using ->
returnRn (SpecSig new_v new_ty new_using src_loc)
where
rn_using Nothing = returnRn Nothing
renameSig (InlineSig v src_loc)
= pushSrcLocRn src_loc $
- lookupRn v `thenRn` \ new_v ->
+ lookupBndrRn v `thenRn` \ new_v ->
returnRn (InlineSig new_v src_loc)
-
-renameSig (DeforestSig v src_loc)
- = pushSrcLocRn src_loc $
- lookupRn v `thenRn` \ new_v ->
- returnRn (DeforestSig new_v src_loc)
-
-renameSig (MagicUnfoldingSig v str src_loc)
- = pushSrcLocRn src_loc $
- lookupRn v `thenRn` \ new_v ->
- returnRn (MagicUnfoldingSig new_v str src_loc)
\end{code}
Checking for distinct signatures; oh, so boring
\begin{code}
-cmp_sig :: RenamedSig -> RenamedSig -> TAG_
-cmp_sig (Sig n1 _ _) (Sig n2 _ _) = n1 `cmp` n2
-cmp_sig (InlineSig n1 _) (InlineSig n2 _) = n1 `cmp` n2
-cmp_sig (MagicUnfoldingSig n1 _ _) (MagicUnfoldingSig n2 _ _) = n1 `cmp` n2
-cmp_sig (SpecSig n1 ty1 _ _) (SpecSig n2 ty2 _ _)
+cmp_sig :: RenamedSig -> RenamedSig -> Ordering
+cmp_sig (Sig n1 _ _) (Sig n2 _ _) = n1 `compare` n2
+cmp_sig (InlineSig n1 _) (InlineSig n2 _) = n1 `compare` n2
+cmp_sig (SpecInstSig ty1 _) (SpecInstSig ty2 _) = cmpHsType compare ty1 ty2
+cmp_sig (SpecSig n1 ty1 _ _) (SpecSig n2 ty2 _ _)
= -- may have many specialisations for one value;
-- but not ones that are exactly the same...
- thenCmp (n1 `cmp` n2) (cmpHsType cmp ty1 ty2)
+ thenCmp (n1 `compare` n2) (cmpHsType compare ty1 ty2)
cmp_sig other_1 other_2 -- Tags *must* be different
- | (sig_tag other_1) _LT_ (sig_tag other_2) = LT_
- | otherwise = GT_
+ | (sig_tag other_1) _LT_ (sig_tag other_2) = LT
+ | otherwise = GT
sig_tag (Sig n1 _ _) = (ILIT(1) :: FAST_INT)
sig_tag (SpecSig n1 _ _ _) = ILIT(2)
sig_tag (InlineSig n1 _) = ILIT(3)
-sig_tag (MagicUnfoldingSig n1 _ _) = ILIT(4)
-sig_tag (DeforestSig n1 _) = ILIT(5)
+sig_tag (SpecInstSig _ _) = ILIT(5)
sig_tag _ = panic# "tag(RnBinds)"
-
-sig_name (Sig n _ _) = n
-sig_name (ClassOpSig n _ _ _) = n
-sig_name (SpecSig n _ _ _) = n
-sig_name (InlineSig n _) = n
-sig_name (MagicUnfoldingSig n _ _) = n
\end{code}
%************************************************************************
\begin{code}
dupSigDeclErr (sig:sigs)
= pushSrcLocRn loc $
- addErrRn (\sty -> ppSep [ppStr "more than one",
- ppStr what_it_is, ppStr "given for",
- ppQuote (ppr sty (sig_name sig))])
+ addErrRn (sep [ptext SLIT("Duplicate"),
+ ptext what_it_is <> colon,
+ ppr sig])
where
(what_it_is, loc) = sig_doc sig
unknownSigErr sig
= pushSrcLocRn loc $
- addErrRn (\sty -> ppSep [ppStr flavour, ppStr "but no definition for",
- ppQuote (ppr sty (sig_name sig))])
+ addErrRn (sep [ptext SLIT("Misplaced"),
+ ptext what_it_is <> colon,
+ ppr sig])
where
- (flavour, loc) = sig_doc sig
+ (what_it_is, loc) = sig_doc sig
-sig_doc (Sig _ _ loc) = ("type signature",loc)
-sig_doc (ClassOpSig _ _ _ loc) = ("class-method type signature", loc)
-sig_doc (SpecSig _ _ _ loc) = ("SPECIALIZE pragma",loc)
-sig_doc (InlineSig _ loc) = ("INLINE pragma",loc)
-sig_doc (MagicUnfoldingSig _ _ loc) = ("MAGIC_UNFOLDING pragma",loc)
+sig_doc (Sig _ _ loc) = (SLIT("type signature"),loc)
+sig_doc (ClassOpSig _ _ _ loc) = (SLIT("class-method type signature"), loc)
+sig_doc (SpecSig _ _ _ loc) = (SLIT("SPECIALISE pragma"),loc)
+sig_doc (InlineSig _ loc) = (SLIT("INLINE pragma"),loc)
+sig_doc (SpecInstSig _ loc) = (SLIT("SPECIALISE instance pragma"),loc)
-missingSigErr var sty
- = ppSep [ppStr "a definition but no type signature for", ppQuote (ppr sty var)]
+missingSigErr var
+ = sep [ptext SLIT("Definition but no type signature for"), quotes (ppr var)]
-methodBindErr mbind sty
- = ppHang (ppStr "Can't handle multiple methods defined by one pattern binding")
- 4 (ppr sty mbind)
+methodBindErr mbind
+ = hang (ptext SLIT("Can't handle multiple methods defined by one pattern binding"))
+ 4 (ppr mbind)
\end{code}
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