diff options
Diffstat (limited to 'compiler/GHC/Hs/Expr.hs')
| -rw-r--r-- | compiler/GHC/Hs/Expr.hs | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/compiler/GHC/Hs/Expr.hs b/compiler/GHC/Hs/Expr.hs index f9d4c559f0..3152571508 100644 --- a/compiler/GHC/Hs/Expr.hs +++ b/compiler/GHC/Hs/Expr.hs @@ -1834,8 +1834,8 @@ data StmtLR idL idR body -- body should always be (LHs**** idR) (LPat idL) body (SyntaxExpr idR) -- The (>>=) operator; see Note [The type of bind in Stmts] - (SyntaxExpr idR) -- The fail operator - -- The fail operator is noSyntaxExpr + (Maybe (SyntaxExpr idR)) -- The fail operator + -- The fail operator is Nothing -- if the pattern match can't fail -- See Note [NoSyntaxExpr] (2) @@ -2003,13 +2003,14 @@ data ApplicativeArg idL , is_body_stmt :: Bool -- True <=> was a BodyStmt -- False <=> was a BindStmt -- See Note [Applicative BodyStmt] - , fail_operator :: (SyntaxExpr idL) -- The fail operator + , fail_operator :: Maybe (SyntaxExpr idL) -- The fail operator -- The fail operator is needed if this is a BindStmt -- where the pattern can fail. E.g.: -- (Just a) <- stmt -- The fail operator will be invoked if the pattern -- match fails. - -- The fail operator is noSyntaxExpr + -- It is also used for guards in MonadComprehensions. + -- The fail operator is Nothing -- if the pattern match can't fail -- See Note [NoSyntaxExpr] (2) } @@ -2252,7 +2253,7 @@ pprStmt (ApplicativeStmt _ args mb_join) [ppr (BodyStmt (panic "pprStmt") expr noSyntaxExpr noSyntaxExpr :: ExprStmt (GhcPass idL))] | otherwise = - [ppr (BindStmt (panic "pprStmt") pat expr noSyntaxExpr noSyntaxExpr + [ppr (BindStmt (panic "pprStmt") pat expr noSyntaxExpr Nothing :: ExprStmt (GhcPass idL))] flattenArg (_, ApplicativeArgMany _ stmts _ _) = concatMap flattenStmt stmts @@ -2278,7 +2279,7 @@ pprArg (ApplicativeArgOne _ pat expr isBody _) ppr (BodyStmt (panic "pprStmt") expr noSyntaxExpr noSyntaxExpr :: ExprStmt (GhcPass idL)) | otherwise = - ppr (BindStmt (panic "pprStmt") pat expr noSyntaxExpr noSyntaxExpr + ppr (BindStmt (panic "pprStmt") pat expr noSyntaxExpr Nothing :: ExprStmt (GhcPass idL)) pprArg (ApplicativeArgMany _ stmts return pat) = ppr pat <+> |