{-# LANGUAGE CPP #-} #ifdef PRAGMA_DERIVE_TYPEABLE {-# LANGUAGE DeriveDataTypeable #-} #else {-# OPTIONS -fglasgow-exts #-} #endif -- This file is Test/Fail.hs. -- ghc --make -optP-DPRAGMA_DERIVE_TYPEABLE -XCPP Test.Fail module Test.Fail where import Data.Generics data Fail = Fail deriving Typeable
If compile this wih the command ghc --make -optP-DPRAGMA_DERIVE_TYPEABLE -XCPP Test.Fail then I get this error from ghc-6.10.1:
[1 of 1] Compiling Test.Fail ( Test\Fail.hs, Test\Fail.o )
Test\Fail.hs:11:26: Can't make a derived instance of `Typeable Fail' (You need -XDeriveDataTypeable to derive an instance for this class) In the data type declaration for `Fail'
No response. I'd like to know if this is a bug (that's what it looks like to me), or just a mistake I've made. Thanks, Alistair