import ParserCoreUtils
import Ratio
import Char
-import Numeric( readFloat )
+import qualified Numeric( readFloat, readDec )
isNameChar c = isAlpha c || isDigit c || (c == '_') || (c == '\'')
isKeywordChar c = isAlpha c || (c == '_')
("_",rest) -> cont TKwild rest
_ -> failP "invalid keyword" ('%':cs)
+
+#if __GLASGOW_HASKELL__ >= 504
+-- The readFloat in the Numeric library will do the job
+
+readFloat :: (RealFrac a) => ReadS a
+readFloat = Numeric.readFloat
+
+#else
+-- Haskell 98's Numeric.readFloat used to have a bogusly restricted signature
+-- so it was incapable of reading a rational.
+-- So for GHCs that have that old bogus library, here is the code, written out longhand.
+
+readFloat r = [(fromRational ((n%1)*10^^(k-d)),t) | (n,d,s) <- readFix r,
+ (k,t) <- readExp s] ++
+ [ (0/0, t) | ("NaN",t) <- lex r] ++
+ [ (1/0, t) | ("Infinity",t) <- lex r]
+ where
+ readFix r = [(read (ds++ds'), length ds', t)
+ | (ds,d) <- lexDigits r,
+ (ds',t) <- lexFrac d ]
+
+ lexFrac ('.':ds) = lexDigits ds
+ lexFrac s = [("",s)]
+
+ readExp (e:s) | e `elem` "eE" = readExp' s
+ readExp s = [(0,s)]
+
+ readExp' ('-':s) = [(-k,t) | (k,t) <- Numeric.readDec s]
+ readExp' ('+':s) = Numeric.readDec s
+ readExp' s = Numeric.readDec s
+
+lexDigits :: ReadS String
+lexDigits s = case span isDigit s of
+ (cs,s') | not (null cs) -> [(cs,s')]
+ otherwise -> []
+#endif
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