rnExpr expr `thenRn` \ (expr',fvExpr) ->
returnRn (HsLet binds' expr', fvExpr)
-rnExpr (HsDo do_or_lc stmts src_loc)
+rnExpr e@(HsDo do_or_lc stmts src_loc)
= pushSrcLocRn src_loc $
lookupImplicitOccRn monadClass_RDR `thenRn` \ monad ->
rnStmts rnExpr stmts `thenRn` \ (stmts', fvs) ->
+ -- check the statement list ends in an expression
+ case last stmts' of {
+ ExprStmt _ _ -> returnRn () ;
+ ReturnStmt _ -> returnRn () ; -- for list comprehensions
+ _ -> addErrRn (doStmtListErr e)
+ } `thenRn_`
returnRn (HsDo do_or_lc stmts' src_loc, fvs `addOneFV` monad)
rnExpr (ExplicitList exps)
patSynErr e
= sep [ptext SLIT("Pattern syntax in expression context:"),
nest 4 (ppr e)]
+
+doStmtListErr e
+ = sep [ptext SLIT("`do' statements must end in expression:"),
+ nest 4 (ppr e)]
\end{code}