import MatchLit ( matchLiterals )
import PrelInfo ( pAT_ERROR_ID )
import Type ( isUnLiftedType, splitAlgTyConApp,
- Type
+ mkTyVarTys, Type
)
import TysPrim ( intPrimTy, charPrimTy, floatPrimTy, doublePrimTy,
addrPrimTy, wordPrimTy
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 ()
-- 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' = dataConArgTys 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,
-- LitPats: the desugarer only sees these at well-known types
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 lit_ty 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 (tidyLitPat 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:
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) ->
+ = flattenMatches kind matches `thenDs` \ (result_ty, eqns_info) ->
let
EqnInfo _ _ arg_pats _ : _ = eqns_info
in
projects / ghc-hetmet.git / blobdiff