#include "HsVersions.h"
-import {-# SOURCE #-} DsExpr ( dsExpr, dsLet )
-
-import CmdLineOpts ( opt_WarnIncompletePatterns, opt_WarnOverlappingPatterns,
- opt_WarnSimplePatterns
- )
+import CmdLineOpts ( DynFlag(..), dopt )
import HsSyn
-import TcHsSyn ( TypecheckedPat, TypecheckedMatch )
+import TcHsSyn ( TypecheckedPat, TypecheckedMatch, TypecheckedMatchContext )
import DsHsSyn ( outPatType )
import Check ( check, ExhaustivePat )
import CoreSyn
-import CoreUtils ( coreExprType )
+import CoreUtils ( bindNonRec )
import DsMonad
import DsGRHSs ( dsGRHSs )
import DsUtils
import Id ( idType, recordSelectorFieldLabel, Id )
-import DataCon ( dataConFieldLabels, dataConArgTys )
+import DataCon ( dataConFieldLabels, dataConInstOrigArgTys )
import MatchCon ( matchConFamily )
import MatchLit ( matchLiterals )
-import PrelVals ( pAT_ERROR_ID )
-import Type ( isUnLiftedType, splitAlgTyConApp,
- Type
- )
-import TysPrim ( intPrimTy, charPrimTy, floatPrimTy, doublePrimTy,
- addrPrimTy, wordPrimTy
- )
-import TysWiredIn ( nilDataCon, consDataCon, mkTupleTy, mkListTy,
- charTy, charDataCon, intTy, intDataCon,
- floatTy, floatDataCon, doubleTy, tupleCon,
- doubleDataCon, addrTy,
- addrDataCon, wordTy, wordDataCon,
- mkUnboxedTupleTy, unboxedTupleCon
- )
+import PrelInfo ( pAT_ERROR_ID )
+import Type ( splitAlgTyConApp, mkTyVarTys, Type )
+import TysWiredIn ( nilDataCon, consDataCon, mkTupleTy, mkListTy, tupleCon )
+import BasicTypes ( Boxity(..) )
import UniqSet
+import ErrUtils ( addWarnLocHdrLine, dontAddErrLoc )
import Outputable
\end{code}
-> [EquationInfo] -- Info about patterns, etc. (type synonym below)
-> DsM MatchResult -- Desugared result!
-matchExport vars qs@((EqnInfo _ ctx _ (MatchResult _ _)) : _)
+
+matchExport vars qs
+ = getDOptsDs `thenDs` \ dflags ->
+ matchExport_really dflags vars qs
+
+matchExport_really dflags vars qs@((EqnInfo _ ctx _ (MatchResult _ _)) : _)
| incomplete && shadow =
dsShadowWarn ctx eqns_shadow `thenDs` \ () ->
dsIncompleteWarn ctx pats `thenDs` \ () ->
| otherwise =
match vars qs
where (pats,indexs) = check qs
- incomplete = opt_WarnIncompletePatterns && (length pats /= 0)
- shadow = opt_WarnOverlappingPatterns && sizeUniqSet indexs < no_eqns
+ incomplete = dopt Opt_WarnIncompletePatterns dflags
+ && (length pats /= 0)
+ shadow = dopt Opt_WarnOverlappingPatterns dflags
+ && sizeUniqSet indexs < no_eqns
no_eqns = length qs
unused_eqns = uniqSetToList (mkUniqSet [1..no_eqns] `minusUniqSet` indexs)
eqns_shadow = map (\n -> qs!!(n - 1)) unused_eqns
\end{code}
-This variable shows the maximun number of lines of output generated for warnings.
-It will limit the number of patterns/equations displayed to maximum_output.
+This variable shows the maximum number of lines of output generated for warnings.
+It will limit the number of patterns/equations displayed to@ maximum_output@.
(ToDo: add command-line option?)
maximum_output = 4
\end{code}
-The next two functions creates the warning message.
+The next two functions create the warning message.
\begin{code}
dsShadowWarn :: DsMatchContext -> [EquationInfo] -> DsM ()
dsShadowWarn ctx@(DsMatchContext kind _ _) qs = dsWarn warn
where
warn | length qs > maximum_output
- = hang (pp_context ctx (ptext SLIT("are overlapped")))
- 12 ((vcat $ map (ppr_eqn kind) (take maximum_output qs))
- $$ ptext SLIT("..."))
+ = pp_context ctx (ptext SLIT("are overlapped"))
+ (\ f -> vcat (map (ppr_eqn f kind) (take maximum_output qs)) $$
+ ptext SLIT("..."))
| otherwise
- = hang (pp_context ctx (ptext SLIT("are overlapped")))
- 12 (vcat $ map (ppr_eqn kind) qs)
+ = pp_context ctx (ptext SLIT("are overlapped"))
+ (\ f -> vcat $ map (ppr_eqn f kind) qs)
+
dsIncompleteWarn :: DsMatchContext -> [ExhaustivePat] -> DsM ()
dsIncompleteWarn ctx@(DsMatchContext kind _ _) pats = dsWarn warn
where
- warn | length pats > maximum_output
- = hang (pp_context ctx (ptext SLIT("are non-exhaustive")))
- 12 (hang (ptext SLIT("Patterns not recognized:"))
- 4 ((vcat $ map (ppr_incomplete_pats kind) (take maximum_output pats))
- $$ ptext SLIT("...")))
- | otherwise
- = hang (pp_context ctx (ptext SLIT("are non-exhaustive")))
- 12 (hang (ptext SLIT("Patterns not recognized:"))
- 4 (vcat $ map (ppr_incomplete_pats kind) pats))
-
-pp_context NoMatchContext msg = ptext SLIT("Some match(es)") <+> msg
-
-pp_context (DsMatchContext kind pats loc) msg
- = hang (hcat [ppr loc, ptext SLIT(": ")])
- 4 (hang message
- 4 (pp_match kind pats))
- where
- message = ptext SLIT("Pattern match(es)") <+> msg
-
- pp_match (FunMatch fun) pats
- = hsep [ptext SLIT("in the definition of function"), quotes (ppr fun)]
-
- pp_match CaseMatch pats
- = hang (ptext SLIT("in a group of case alternatives beginning:"))
- 4 (ppr_pats pats)
-
- pp_match PatBindMatch pats
- = hang (ptext SLIT("in a pattern binding:"))
- 4 (ppr_pats pats)
-
- pp_match LambdaMatch pats
- = hang (ptext SLIT("in a lambda abstraction:"))
- 4 (ppr_pats pats)
-
- pp_match DoBindMatch pats
- = hang (ptext SLIT("in a `do' pattern binding:"))
- 4 (ppr_pats pats)
-
- pp_match ListCompMatch pats
- = hang (ptext SLIT("in a `list comprension' pattern binding:"))
- 4 (ppr_pats pats)
-
- pp_match LetMatch pats
- = hang (ptext SLIT("in a `let' pattern binding:"))
- 4 (ppr_pats pats)
+ warn = pp_context ctx (ptext SLIT("are non-exhaustive"))
+ (\f -> hang (ptext SLIT("Patterns not matched:"))
+ 4 ((vcat $ map (ppr_incomplete_pats kind)
+ (take maximum_output pats))
+ $$ dots))
+
+ dots | length pats > maximum_output = ptext SLIT("...")
+ | otherwise = empty
+
+pp_context NoMatchContext msg rest_of_msg_fun
+ = dontAddErrLoc (ptext SLIT("Some match(es)") <+> hang msg 8 (rest_of_msg_fun id))
+
+pp_context (DsMatchContext kind pats loc) msg rest_of_msg_fun
+ = addWarnLocHdrLine loc
+ (ptext SLIT("Pattern match(es)") <+> msg)
+ (sep [ppr_match <> char ':', nest 4 (rest_of_msg_fun pref)])
+ where
+ (ppr_match, pref)
+ = case kind of
+ FunRhs fun -> (pprMatchContext kind, \ pp -> ppr fun <+> pp)
+ other -> (pprMatchContext kind <+> ppr_pats pats, \ pp -> pp)
ppr_pats pats = sep (map ppr pats)
-separator (FunMatch _) = SLIT("=")
-separator (CaseMatch) = SLIT("->")
-separator (LambdaMatch) = SLIT("->")
-separator (PatBindMatch) = panic "When is this used?"
-separator (DoBindMatch) = SLIT("<-")
-separator (ListCompMatch) = SLIT("<-")
-separator (LetMatch) = SLIT("=")
-
-ppr_shadow_pats kind pats = sep [ppr_pats pats, ptext (separator kind), ptext SLIT("...")]
+ppr_shadow_pats kind pats
+ = sep [ppr_pats pats, ptext (matchSeparator kind), ptext SLIT("...")]
ppr_incomplete_pats kind (pats,[]) = ppr_pats pats
ppr_incomplete_pats kind (pats,constraints) =
sep (map ppr_constraint constraints)]
-ppr_constraint (var,pats) = sep [ppr var, ptext SLIT("`not_elem`"), ppr pats]
+ppr_constraint (var,pats) = sep [ppr var, ptext SLIT("`notElem`"), ppr pats]
-ppr_eqn kind (EqnInfo _ _ pats _) = ppr_shadow_pats kind pats
+ppr_eqn prefixF kind (EqnInfo _ _ pats _) = prefixF (ppr_shadow_pats kind pats)
\end{code}
unmix_eqns [] = []
unmix_eqns [eqn] = [ [eqn] ]
unmix_eqns (eq1@(EqnInfo _ _ (p1:p1s) _) : eq2@(EqnInfo _ _ (p2:p2s) _) : eqs)
- = if ( (irrefutablePat p1 && irrefutablePat p2)
- || (isConPat p1 && isConPat p2)
- || (isLitPat p1 && isLitPat p2) ) then
+ = if ( (isWildPat p1 && isWildPat p2)
+ || (isConPat p1 && isConPat p2)
+ || (isLitPat p1 && isLitPat p2) ) then
eq1 `tack_onto` unmixed_rest
else
[ eq1 ] : unmixed_rest
-- DsM'd because of internal call to "match".
-- "tidy1" does the interesting stuff, looking at
-- one pattern and fiddling the list of bindings.
+ --
+ -- POST CONDITION: head pattern in the EqnInfo is
+ -- WildPat
+ -- ConPat
+ -- NPat
+ -- LitPat
+ -- NPlusKPat
+ -- but no other
+
tidyEqnInfo v (EqnInfo n ctx (pat : pats) match_result)
= tidy1 v pat match_result `thenDs` \ (pat', match_result') ->
returnDs (EqnInfo n ctx (pat' : pats) match_result')
-- re-express <con-something> as (ConPat ...) [directly]
-tidy1 v (RecPat data_con pat_ty tvs dicts rpats) match_result
- = returnDs (ConPat data_con pat_ty tvs dicts pats, match_result)
+tidy1 v (RecPat data_con pat_ty ex_tvs dicts rpats) match_result
+ | null rpats
+ = -- Special case for C {}, which can be used for
+ -- a constructor that isn't declared to have
+ -- fields at all
+ returnDs (ConPat data_con pat_ty ex_tvs dicts (map WildPat con_arg_tys'), match_result)
+
+ | otherwise
+ = returnDs (ConPat data_con pat_ty ex_tvs dicts pats, match_result)
where
pats = map mk_pat tagged_arg_tys
-- Boring stuff to find the arg-tys of the constructor
(_, inst_tys, _) = splitAlgTyConApp pat_ty
- con_arg_tys' = dataConArgTys data_con inst_tys
+ con_arg_tys' = dataConInstOrigArgTys data_con (inst_tys ++ mkTyVarTys ex_tvs)
tagged_arg_tys = con_arg_tys' `zip` (dataConFieldLabels data_con)
-- mk_pat picks a WildPat of the appropriate type for absent fields,
(ConPat nilDataCon list_ty [] [] [])
pats
-tidy1 v (TuplePat pats True{-boxed-}) match_result
- = returnDs (tuple_ConPat, match_result)
- where
- arity = length pats
- tuple_ConPat
- = ConPat (tupleCon arity)
- (mkTupleTy arity (map outPatType pats)) [] []
- pats
-
-tidy1 v (TuplePat pats False{-unboxed-}) match_result
+tidy1 v (TuplePat pats boxity) match_result
= returnDs (tuple_ConPat, match_result)
where
arity = length pats
tuple_ConPat
- = ConPat (unboxedTupleCon arity)
- (mkUnboxedTupleTy arity (map outPatType pats)) [] []
+ = ConPat (tupleCon boxity arity)
+ (mkTupleTy boxity arity (map outPatType pats)) [] []
pats
tidy1 v (DictPat dicts methods) match_result
= case num_of_d_and_ms of
- 0 -> tidy1 v (TuplePat [] True) match_result
+ 0 -> tidy1 v (TuplePat [] Boxed) match_result
1 -> tidy1 v (head dict_and_method_pats) match_result
- _ -> tidy1 v (TuplePat dict_and_method_pats True) match_result
+ _ -> tidy1 v (TuplePat dict_and_method_pats Boxed) match_result
where
num_of_d_and_ms = length dicts + length methods
dict_and_method_pats = map VarPat (dicts ++ methods)
-
--- deeply ugly mangling for some (common) NPats/LitPats
-
--- LitPats: the desugarer only sees these at well-known types
-
+-- LitPats: we *might* be able to replace these w/ a simpler form
tidy1 v pat@(LitPat lit lit_ty) match_result
- | isUnLiftedType lit_ty
- = returnDs (pat, match_result)
-
- | lit_ty == charTy
- = returnDs (ConPat charDataCon charTy [] [] [LitPat (mk_char lit) charPrimTy],
- match_result)
-
- | otherwise = pprPanic "tidy1:LitPat:" (ppr pat)
- where
- mk_char (HsChar c) = HsCharPrim c
+ = returnDs (tidyLitPat lit pat, match_result)
-- NPats: we *might* be able to replace these w/ a simpler form
-
-
tidy1 v pat@(NPat lit lit_ty _) match_result
- = returnDs (better_pat, match_result)
- where
- better_pat
- | lit_ty == charTy = ConPat charDataCon lit_ty [] [] [LitPat (mk_char lit) charPrimTy]
- | lit_ty == intTy = ConPat intDataCon lit_ty [] [] [LitPat (mk_int lit) intPrimTy]
- | lit_ty == wordTy = ConPat wordDataCon lit_ty [] [] [LitPat (mk_word lit) wordPrimTy]
- | lit_ty == addrTy = ConPat addrDataCon lit_ty [] [] [LitPat (mk_addr lit) addrPrimTy]
- | lit_ty == floatTy = ConPat floatDataCon lit_ty [] [] [LitPat (mk_float lit) floatPrimTy]
- | lit_ty == doubleTy = ConPat doubleDataCon lit_ty [] [] [LitPat (mk_double lit) doublePrimTy]
-
- -- Convert the literal pattern "" to the constructor pattern [].
- | null_str_lit lit = ConPat nilDataCon lit_ty [] [] []
-
- | otherwise = pat
-
- mk_int (HsInt i) = HsIntPrim i
- mk_int l@(HsLitLit s) = l
-
- mk_char (HsChar c) = HsCharPrim c
- mk_char l@(HsLitLit s) = l
-
- mk_word l@(HsLitLit s) = l
-
- mk_addr l@(HsLitLit s) = l
-
- mk_float (HsInt i) = HsFloatPrim (fromInteger i)
- mk_float (HsFrac f) = HsFloatPrim f
- mk_float l@(HsLitLit s) = l
-
- mk_double (HsInt i) = HsDoublePrim (fromInteger i)
- mk_double (HsFrac f) = HsDoublePrim f
- mk_double l@(HsLitLit s) = l
-
- null_str_lit (HsString s) = _NULL_ s
- null_str_lit other_lit = False
+ = returnDs (tidyNPat lit lit_ty pat, match_result)
-- and everything else goes through unchanged...
= returnDs (non_interesting_pat, match_result)
\end{code}
-PREVIOUS matchTwiddled STUFF:
+\noindent
+{\bf Previous @matchTwiddled@ stuff:}
Now we get to the only interesting part; note: there are choices for
translation [from Simon's notes]; translation~1:
matchUnmixedEqns [] _ = panic "matchUnmixedEqns: no names"
matchUnmixedEqns all_vars@(var:vars) eqns_info
- | irrefutablePat first_pat
- = ASSERT( irrefutablePats column_1_pats ) -- Sanity check
+ | isWildPat first_pat
+ = ASSERT( all isWildPat column_1_pats ) -- Sanity check
-- Real true variables, just like in matchVar, SLPJ p 94
+ -- No binding to do: they'll all be wildcards by now (done in tidy)
match vars remaining_eqns_info
| isConPat first_pat
\end{enumerate}
\begin{code}
-matchWrapper :: DsMatchKind -- For shadowing warning messages
- -> [TypecheckedMatch] -- Matches being desugared
- -> String -- Error message if the match fails
+matchWrapper :: TypecheckedMatchContext -- For shadowing warning messages
+ -> [TypecheckedMatch] -- Matches being desugared
-> DsM ([Id], CoreExpr) -- Results
\end{code}
- a special case for the common ...:
- just one Match
- lots of (all?) unfailable pats
- e.g.,
- f x y z = ....
-
- This special case have been ``undone'' due to problems with the new warnings
- messages (Check.lhs.check). We need there the name of the variables to be able to
- print later the equation. JJQC 30-11-97
-
-\begin{old_code}
-matchWrapper kind [(PatMatch (VarPat var) match)] error_string
- = matchWrapper kind [match] error_string `thenDs` \ (vars, core_expr) ->
- returnDs (var:vars, core_expr)
-
-matchWrapper kind [(PatMatch (WildPat ty) match)] error_string
- = newSysLocalDs ty `thenDs` \ var ->
- matchWrapper kind [match] error_string `thenDs` \ (vars, core_expr) ->
- returnDs (var:vars, core_expr)
-
-matchWrapper kind [(GRHSMatch
- (GRHSsAndBindsOut [GRHS [ExprStmt expr _]] binds _))] error_string
- = dsExpr expr `thenDs` \ core_expr ->
- dsLet binds core_expr `thenDs` \ rhs ->
- returnDs ([], rhs)
-\end{old_code}
-
- And all the rest... (general case)
-
-
There is one small problem with the Lambda Patterns, when somebody
writes something similar to:
+\begin{verbatim}
(\ (x:xs) -> ...)
+\end{verbatim}
he/she don't want a warning about incomplete patterns, that is done with
- the flag opt_WarnSimplePatterns.
- This problem also appears in the :
- do patterns, but if the do can fail it creates another equation if the match can
- fail (see DsExpr.doDo function)
- let patterns, are treated by matchSimply
- List Comprension Patterns, are treated by matchSimply also
-
-We can't call matchSimply with Lambda patterns, due to lambda patterns can have more than
+ the flag @opt_WarnSimplePatterns@.
+ This problem also appears in the:
+\begin{itemize}
+\item @do@ patterns, but if the @do@ can fail
+ it creates another equation if the match can fail
+ (see @DsExpr.doDo@ function)
+\item @let@ patterns, are treated by @matchSimply@
+ List Comprension Patterns, are treated by @matchSimply@ also
+\end{itemize}
+
+We can't call @matchSimply@ with Lambda patterns,
+due to the fact that lambda patterns can have more than
one pattern, and match simply only accepts one pattern.
JJQC 30-Nov-1997
-
+
\begin{code}
-matchWrapper kind matches error_string
- = flattenMatches kind matches `thenDs` \ (result_ty, eqns_info) ->
+matchWrapper ctxt matches
+ = getDOptsDs `thenDs` \ dflags ->
+ flattenMatches ctxt matches `thenDs` \ (result_ty, eqns_info) ->
let
EqnInfo _ _ arg_pats _ : _ = eqns_info
+ error_string = matchContextErrString ctxt
in
- mapDs selectMatchVar arg_pats `thenDs` \ new_vars ->
- match_fun new_vars eqns_info `thenDs` \ match_result ->
+ mapDs selectMatchVar arg_pats `thenDs` \ new_vars ->
+ match_fun dflags new_vars eqns_info `thenDs` \ match_result ->
mkErrorAppDs pAT_ERROR_ID result_ty error_string `thenDs` \ fail_expr ->
extractMatchResult match_result fail_expr `thenDs` \ result_expr ->
returnDs (new_vars, result_expr)
- where match_fun = case kind of
- LambdaMatch | opt_WarnSimplePatterns -> matchExport
- | otherwise -> match
- _ -> matchExport
+ where match_fun dflags
+ = case ctxt of
+ LambdaExpr | dopt Opt_WarnSimplePatterns dflags -> matchExport
+ | otherwise -> match
+ _ -> matchExport
\end{code}
%************************************************************************
\begin{code}
matchSimply :: CoreExpr -- Scrutinee
- -> DsMatchKind -- Match kind
+ -> TypecheckedMatchContext -- Match kind
-> TypecheckedPat -- Pattern it should match
-> CoreExpr -- Return this if it matches
-> CoreExpr -- Return this if it doesn't
-> MatchResult -> DsM MatchResult
matchSinglePat (Var var) ctx pat match_result
- = match_fn [var] [EqnInfo 1 ctx [pat] match_result]
+ = getDOptsDs `thenDs` \ dflags ->
+ match_fn dflags [var] [EqnInfo 1 ctx [pat] match_result]
where
- match_fn | opt_WarnSimplePatterns = matchExport
- | otherwise = match
+ match_fn dflags
+ | dopt Opt_WarnSimplePatterns dflags = matchExport
+ | otherwise = match
matchSinglePat scrut ctx pat match_result
= selectMatchVar pat `thenDs` \ var ->
This is actually local to @matchWrapper@.
\begin{code}
-flattenMatches
- :: DsMatchKind
- -> [TypecheckedMatch]
- -> DsM (Type, [EquationInfo])
+flattenMatches :: TypecheckedMatchContext
+ -> [TypecheckedMatch]
+ -> DsM (Type, [EquationInfo])
flattenMatches kind matches
= mapAndUnzipDs flatten_match (matches `zip` [1..]) `thenDs` \ (result_tys, eqn_infos) ->
ASSERT( all (== result_ty) result_tys )
returnDs (result_ty, eqn_infos)
where
- flatten_match (match, eqn_no) = flatten_match_help [] match eqn_no
-
- flatten_match_help :: [TypecheckedPat] -- Reversed list of patterns encountered so far
- -> TypecheckedMatch
- -> EqnNo
- -> DsM (Type, EquationInfo)
-
- flatten_match_help pats_so_far (PatMatch pat match) n
- = flatten_match_help (pat:pats_so_far) match n
-
- flatten_match_help pats_so_far (GRHSMatch (GRHSsAndBindsOut grhss binds ty)) n
- = dsGRHSs kind pats grhss `thenDs` \ match_result ->
+ flatten_match (Match _ pats _ grhss, n)
+ = dsGRHSs kind pats grhss `thenDs` \ (ty, match_result) ->
getSrcLocDs `thenDs` \ locn ->
- returnDs (ty, EqnInfo n (DsMatchContext kind pats locn) pats
- (adjustMatchResultDs (dsLet binds) match_result))
- -- NB: nested dsLet inside matchResult
- where
- pats = reverse pats_so_far -- They've accumulated in reverse order
-
- flatten_match_help pats_so_far (SimpleMatch expr) n
- = dsExpr expr `thenDs` \ core_expr ->
- getSrcLocDs `thenDs` \ locn ->
- returnDs (coreExprType core_expr,
- EqnInfo n (DsMatchContext kind pats locn) pats
- (cantFailMatchResult core_expr))
- where
- pats = reverse pats_so_far -- They've accumulated in reverse order
+ returnDs (ty, EqnInfo n (DsMatchContext kind pats locn) pats match_result)
\end{code}
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