Improve pretty-printing for Insts

[ghc-hetmet.git] / compiler / typecheck / TcRnMonad.lhs

diff --git a/compiler/typecheck/TcRnMonad.lhs b/compiler/typecheck/TcRnMonad.lhs
index f118f47..68db3a2 100644 (file)
--- a/compiler/typecheck/TcRnMonad.lhs
+++ b/compiler/typecheck/TcRnMonad.lhs
@@ -561,6 +561,19 @@ recoverM recover thing
           Left exn  -> recover
           Right res -> returnM res }
 
+
+-----------------------
+mapAndRecoverM :: (a -> TcRn b) -> [a] -> TcRn [b]
+-- Drop elements of the input that fail, so the result
+-- list can be shorter than the argument list
+mapAndRecoverM f []     = return []
+mapAndRecoverM f (x:xs) = do { mb_r <- tryM (f x)
+                            ; rs <- mapAndRecoverM f xs
+                            ; return (case mb_r of
+                                         Left _  -> rs
+                                         Right r -> r:rs) }
+                       
+
 -----------------------
 tryTc :: TcRn a -> TcRn (Messages, Maybe a)
 -- (tryTc m) executes m, and returns