IF_NOT_GHC(applyToSnd COMMA foldPair COMMA)
unzipWith,
+ -- tracing (abstract away from lib home)
+ trace,
+
-- error handling
panic, panic#, assertPanic
import FastString ( FastString )
import List ( zipWith4 )
+import GlaExts ( trace )
infixr 9 `thenCmp`
\end{code}