improve the documentation for throwErrnoIfRetry

[ghc-base.git] / Foreign / C / Error.hs

diff --git a/Foreign/C/Error.hs b/Foreign/C/Error.hs
index ea38694..55358eb 100644 (file)
--- a/Foreign/C/Error.hs
+++ b/Foreign/C/Error.hs
@@ -358,8 +358,9 @@ throwErrnoIfRetry pred loc f  =
           else throwErrno loc
       else return res
 
--- | as 'throwErrnoIfRetry', but checks for operations that would block and
--- executes an alternative action before retrying in that case.
+-- | as 'throwErrnoIfRetry', but additionlly if the operation 
+-- yields the error code 'eAGAIN' or 'eWOULDBLOCK', an alternative
+-- action is executed before retrying.
 --
 throwErrnoIfRetryMayBlock
                 :: (a -> Bool)  -- ^ predicate to apply to the result value
@@ -378,7 +379,8 @@ throwErrnoIfRetryMayBlock pred loc f on_block  =
         if err == eINTR
           then throwErrnoIfRetryMayBlock pred loc f on_block
           else if err == eWOULDBLOCK || err == eAGAIN
-                 then do on_block; throwErrnoIfRetryMayBlock pred loc f on_block
+                 then do _ <- on_block
+                         throwErrnoIfRetryMayBlock pred loc f on_block
                  else throwErrno loc
       else return res