Use explicit language extensions & remove extension fields from base.cabal

[ghc-base.git] / Data / Complex.hs

diff --git a/Data/Complex.hs b/Data/Complex.hs
index 6ebbfcb..9765eda 100644 (file)
--- a/Data/Complex.hs
+++ b/Data/Complex.hs
@@ -1,3 +1,5 @@
+{-# LANGUAGE CPP, DeriveDataTypeable #-}
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Complex
@@ -65,7 +67,11 @@ infix  6  :+
 data (RealFloat a) => Complex a
   = !a :+ !a    -- ^ forms a complex number from its real and imaginary
                 -- rectangular components.
+# if __GLASGOW_HASKELL__
+        deriving (Eq, Show, Read, Data)
+# else
         deriving (Eq, Show, Read)
+# endif
 
 -- -----------------------------------------------------------------------------
 -- Functions over Complex
@@ -194,4 +200,4 @@ instance  (RealFloat a) => Floating (Complex a) where
 
     asinh z        =  log (z + sqrt (1+z*z))
     acosh z        =  log (z + (z+1) * sqrt ((z-1)/(z+1)))
-    atanh z        =  log ((1+z) / sqrt (1-z*z))
+    atanh z        =  0.5 * log ((1.0+z) / (1.0-z))