-- Stability : provisional
-- Portability : portable
--
--- $Id: Numeric.hs,v 1.5 2002/02/12 10:52:18 simonmar Exp $
+-- $Id: Numeric.hs,v 1.6 2002/04/11 12:03:43 simonpj Exp $
--
-- Odds and ends, mostly functions for reading and showing
-- RealFloat-like kind of values.
import GHC.Num
import GHC.Show
import Data.Maybe
+import Text.ParserCombinators.ReadP( ReadP, readP_to_S, pfail )
+import qualified Text.Read.Lex as L
#endif
#ifdef __HUGS__
import Array
#endif
+
+-- *********************************************************
+-- * *
+-- \subsection{Reading}
+-- * *
+-- *********************************************************
+
+readInt :: Num a => a -> (Char -> Bool) -> (Char -> Int) -> ReadS a
+readInt base isDigit valDigit = readP_to_S (L.readIntP base isDigit valDigit)
+
+readOct, readDec, readHex :: Num a => ReadS a
+readOct = readP_to_S L.readOctP
+readDec = readP_to_S L.readDecP
+readHex = readP_to_S L.readHexP
+
+readFloat :: RealFrac a => ReadS a
+readFloat = readP_to_S readFloatP
+
+readFloatP :: RealFrac a => ReadP a
+readFloatP =
+ do L.Number x <- L.lex
+ case L.numberToRational x of
+ Nothing -> pfail
+ Just y -> return (fromRational y)
+
+-- It's turgid to have readSigned work using list comprehensions,
+-- but it's specified as a ReadS to ReadS transformer
+-- With a bit of luck no one will use it.
+readSigned :: (Real a) => ReadS a -> ReadS a
+readSigned readPos = readParen False read'
+ where read' r = read'' r ++
+ (do
+ ("-",s) <- lex r
+ (x,t) <- read'' s
+ return (-x,t))
+ read'' r = do
+ (str,s) <- lex r
+ (n,"") <- readPos str
+ return (n,s)
+
+
+-- *********************************************************
+-- * *
+-- \subsection{Showing}
+-- * *
+-- *********************************************************
+
+
+
#ifdef __GLASGOW_HASKELL__
showInt :: Integral a => a -> ShowS
showInt n cs