diff options
| -rw-r--r-- | compiler/hsSyn/Convert.lhs | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/compiler/hsSyn/Convert.lhs b/compiler/hsSyn/Convert.lhs index 48844ddc85..4a35fda355 100644 --- a/compiler/hsSyn/Convert.lhs +++ b/compiler/hsSyn/Convert.lhs @@ -327,6 +327,11 @@ cvtBind (TH.ValD (TH.VarP s) body ds) ; returnL $ mkFunBind s' [cl'] } cvtBind (TH.FunD nm cls) + | null cls + = failWith (ptext (sLit "Function binding for") + <+> quotes (text (TH.pprint nm)) + <+> ptext (sLit "has no equations")) + | otherwise = do { nm' <- vNameL nm ; cls' <- mapM cvtClause cls ; returnL $ mkFunBind nm' cls' } @@ -371,7 +376,9 @@ cvtl e = wrapL (cvt e) cvt (CondE x y z) = do { x' <- cvtl x; y' <- cvtl y; z' <- cvtl z ; return $ HsIf x' y' z' } cvt (LetE ds e) = do { ds' <- cvtDecs ds; e' <- cvtl e; return $ HsLet ds' e' } - cvt (CaseE e ms) = do { e' <- cvtl e; ms' <- mapM cvtMatch ms + cvt (CaseE e ms) + | null ms = failWith (ptext (sLit "Case expression with no alternatives")) + | otherwise = do { e' <- cvtl e; ms' <- mapM cvtMatch ms ; return $ HsCase e' (mkMatchGroup ms') } cvt (DoE ss) = cvtHsDo DoExpr ss cvt (CompE ss) = cvtHsDo ListComp ss |