Document the behaviour of unsafeUseAsCStringLen when BS.empty is pass…

…ed (fixes #207)
haskell · Jul 4, 2020 · 136344f · 136344f
1 parent f18af8e
commit 136344f
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/Data/ByteString/Unsafe.hs b/Data/ByteString/Unsafe.hs
@@ -282,5 +282,6 @@ unsafeUseAsCString (PS ps s _) ac = withForeignPtr ps $ \p -> ac (castPtr p `plu
 -- will break referential transparency. To avoid this, use
 -- 'useAsCStringLen', which makes a copy of the original 'ByteString'.
 --
+-- If 'empty' is given, It will pass ('nullPtr', 0).
 unsafeUseAsCStringLen :: ByteString -> (CStringLen -> IO a) -> IO a
 unsafeUseAsCStringLen (PS ps s l) f = withForeignPtr ps $ \p -> f (castPtr p `plusPtr` s,l)