- [datacon] -> do
- let field_tys = DataCon.dataConInstOrigArgTys datacon tyargs
- -- Create a list of wild binders for the fields we don't want
- let wildbndrs = map MkCore.mkWildBinder field_tys
- -- Create a single binder for the field we want
- sel_bndr <- mkInternalVar "sel" (field_tys!!i)
- -- Create a wild binder for the scrutinee
- let scrut_bndr = MkCore.mkWildBinder scrut_ty
- -- Create the case expression
- let binders = take i wildbndrs ++ [sel_bndr] ++ drop (i+1) wildbndrs
- return $ CoreSyn.Case scrut scrut_bndr scrut_ty [(CoreSyn.DataAlt datacon, binders, CoreSyn.Var sel_bndr)]
- dcs -> error $ "CoreTools.mkSelCase: Scrutinee type must have exactly one datacon. Extracting element " ++ (show i) ++ " from '" ++ pprString scrut ++ "' Datacons: " ++ (show dcs) ++ " Type: " ++ (pprString scrut_ty)
- Nothing -> error $ "CoreTools.mkSelCase: Creating extractor case, but scrutinee has no tycon? Extracting element " ++ (show i) ++ " from '" ++ pprString scrut ++ "'" ++ " Type: " ++ (pprString scrut_ty)
+ Just dcs | dc_i < 0 || dc_i >= length dcs -> error $ "\nCoreTools.mkSelCase: Creating extractor case, but datacon index is invalid." ++ error_msg
+ | otherwise -> do
+ let datacon = (dcs!!dc_i)
+ let field_tys = DataCon.dataConInstOrigArgTys datacon tyargs
+ if i < 0 || i >= length field_tys
+ then error $ "\nCoreTools.mkSelCase: Creating extractor case, but field index is invalid." ++ error_msg
+ else do
+ -- Create a list of wild binders for the fields we don't want
+ let wildbndrs = map MkCore.mkWildBinder field_tys
+ -- Create a single binder for the field we want
+ sel_bndr <- mkInternalVar "sel" (field_tys!!i)
+ -- Create a wild binder for the scrutinee
+ let scrut_bndr = MkCore.mkWildBinder scrut_ty
+ -- Create the case expression
+ let binders = take i wildbndrs ++ [sel_bndr] ++ drop (i+1) wildbndrs
+ return $ CoreSyn.Case scrut scrut_bndr scrut_ty [(CoreSyn.DataAlt datacon, binders, CoreSyn.Var sel_bndr)]
+ Nothing -> error $ "CoreTools.mkSelCase: Creating extractor case, but scrutinee has no datacons?" ++ error_msg
+ Nothing -> error $ "CoreTools.mkSelCase: Creating extractor case, but scrutinee has no tycon?" ++ error_msg
+ where
+ scrut_ty = CoreUtils.exprType scrut
+ error_msg = " Extracting element " ++ (show i) ++ " from datacon " ++ (show dc_i) ++ " from '" ++ pprString scrut ++ "'" ++ " Type: " ++ (pprString scrut_ty)