X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FbasicTypes%2FBasicTypes.lhs;h=65002d57ced5bf2fb0d6ffab55b38b0eb7951c90;hp=f07788203a58b6d0bc87c1d1d2ab05026c7a0068;hb=6ddfe9b18d4d280676aab2fa797ddbe6f8a09d6b;hpb=c177e43f99dcd525b78ee0ac8f16c3d42c618e1f

diff --git a/compiler/basicTypes/BasicTypes.lhs b/compiler/basicTypes/BasicTypes.lhs
index f077882..65002d5 100644
--- a/compiler/basicTypes/BasicTypes.lhs
+++ b/compiler/basicTypes/BasicTypes.lhs
@@ -72,13 +72,16 @@ module BasicTypes(
         inlinePragmaActivation, inlinePragmaRuleMatchInfo,
         setInlinePragmaActivation, setInlinePragmaRuleMatchInfo,
 
-	SuccessFlag(..), succeeded, failed, successIf
+	SuccessFlag(..), succeeded, failed, successIf,
+	
+	FractionalLit(..), negateFractionalLit, integralFractionalLit
    ) where
 
 import FastString
 import Outputable
 
 import Data.Data hiding (Fixity)
+import Data.Function (on)
 \end{code}
 
 %************************************************************************
@@ -862,3 +865,35 @@ isEarlyActive (ActiveBefore {}) = True
 isEarlyActive _		        = False
 \end{code}
 
+
+
+\begin{code}
+-- Used (instead of Rational) to represent exactly the floating point literal that we
+-- encountered in the user's source program. This allows us to pretty-print exactly what
+-- the user wrote, which is important e.g. for floating point numbers that can't represented
+-- as Doubles (we used to via Double for pretty-printing). See also #2245.
+data FractionalLit
+  = FL { fl_text :: String         -- How the value was written in the source
+       , fl_value :: Rational      -- Numeric value of the literal
+       }
+  deriving (Data, Typeable)
+
+negateFractionalLit :: FractionalLit -> FractionalLit
+negateFractionalLit (FL { fl_text = '-':text, fl_value = value }) = FL { fl_text = text, fl_value = negate value }
+negateFractionalLit (FL { fl_text = text, fl_value = value }) = FL { fl_text = '-':text, fl_value = negate value }
+
+integralFractionalLit :: Integer -> FractionalLit
+integralFractionalLit i = FL { fl_text = show i, fl_value = fromInteger i }
+
+-- Comparison operations are needed when grouping literals
+-- for compiling pattern-matching (module MatchLit)
+
+instance Eq FractionalLit where
+  (==) = (==) `on` fl_value
+
+instance Ord FractionalLit where
+  compare = compare `on` fl_value
+
+instance Outputable FractionalLit where
+  ppr = text . fl_text
+\end{code}