-- Portability : portable
--
-- Odds and ends, mostly functions for reading and showing
--- RealFloat-like kind of values.
+-- 'RealFloat'-like kind of values.
--
-----------------------------------------------------------------------------
module Numeric (
- fromRat, -- :: (RealFloat a) => Rational -> a
- showSigned, -- :: (Real a) => (a -> ShowS) -> Int -> a -> ShowS
- readSigned, -- :: (Real a) => ReadS a -> ReadS a
+ -- * Showing
- readInt, -- :: (Integral a) => a -> (Char -> Bool)
- -- -> (Char -> Int) -> ReadS a
- readDec, -- :: (Integral a) => ReadS a
- readOct, -- :: (Integral a) => ReadS a
- readHex, -- :: (Integral a) => ReadS a
+ showSigned, -- :: (Real a) => (a -> ShowS) -> Int -> a -> ShowS
- showInt, -- :: Integral a => a -> ShowS
showIntAtBase, -- :: Integral a => a -> (a -> Char) -> a -> ShowS
+ showInt, -- :: Integral a => a -> ShowS
showHex, -- :: Integral a => a -> ShowS
showOct, -- :: Integral a => a -> ShowS
showFFloat, -- :: (RealFloat a) => Maybe Int -> a -> ShowS
showGFloat, -- :: (RealFloat a) => Maybe Int -> a -> ShowS
showFloat, -- :: (RealFloat a) => a -> ShowS
+
+ floatToDigits, -- :: (RealFloat a) => Integer -> a -> ([Int], Int)
+
+ -- * Reading
+
+ -- | /NB:/ 'readInt' is the \'dual\' of 'showIntAtBase',
+ -- and 'readDec' is the \`dual\' of 'showInt'.
+ -- The inconsistent naming is a historical accident.
+
+ readSigned, -- :: (Real a) => ReadS a -> ReadS a
+
+ readInt, -- :: (Integral a) => a -> (Char -> Bool)
+ -- -> (Char -> Int) -> ReadS a
+ readDec, -- :: (Integral a) => ReadS a
+ readOct, -- :: (Integral a) => ReadS a
+ readHex, -- :: (Integral a) => ReadS a
+
readFloat, -- :: (RealFloat a) => ReadS a
- floatToDigits, -- :: (RealFloat a) => Integer -> a -> ([Int], Int)
lexDigits, -- :: ReadS String
+ -- * Miscellaneous
+
+ fromRat, -- :: (RealFloat a) => Rational -> a
+
) where
#ifdef __GLASGOW_HASKELL__
-- -----------------------------------------------------------------------------
-- Reading
-readInt :: Num a => a -> (Char -> Bool) -> (Char -> Int) -> ReadS a
+-- | Reads an /unsigned/ 'Integral' value in an arbitrary base.
+readInt :: Num a
+ => a -- ^ the base
+ -> (Char -> Bool) -- ^ a predicate distinguishing valid digits in this base
+ -> (Char -> Int) -- ^ a function converting a valid digit character to an 'Int'
+ -> ReadS a
readInt base isDigit valDigit = readP_to_S (L.readIntP base isDigit valDigit)
-readOct, readDec, readHex :: Num a => ReadS a
+-- | Read an unsigned number in octal notation.
+readOct :: Num a => ReadS a
readOct = readP_to_S L.readOctP
+
+-- | Read an unsigned number in decimal notation.
+readDec :: Num a => ReadS a
readDec = readP_to_S L.readDecP
+
+-- | Read an unsigned number in hexadecimal notation.
+-- Both upper or lower case letters are allowed.
+readHex :: Num a => ReadS a
readHex = readP_to_S L.readHexP
+-- | Reads an /unsigned/ 'RealFrac' value,
+-- expressed in decimal scientific notation.
readFloat :: RealFrac a => ReadS a
readFloat = readP_to_S readFloatP
-- 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.
+
+-- | Reads a /signed/ 'Real' value, given a reader for an unsigned value.
readSigned :: (Real a) => ReadS a -> ReadS a
readSigned readPos = readParen False read'
where read' r = read'' r ++
-- -----------------------------------------------------------------------------
-- Showing
+-- | Show /non-negative/ 'Integral' numbers in base 10.
showInt :: Integral a => a -> ShowS
showInt n cs
| n < 0 = error "Numeric.showInt: can't show negative numbers"
Maybe Int -> Float -> ShowS,
Maybe Int -> Double -> ShowS #-}
+-- | Show a signed 'RealFloat' value
+-- using scientific (exponential) notation (e.g. @2.45e2@, @1.5e-3@).
+--
+-- In the call @'showEFloat' digs val@, if @digs@ is 'Nothing',
+-- the value is shown to full precision; if @digs@ is @'Just' d@,
+-- then at most @d@ digits after the decimal point are shown.
showEFloat :: (RealFloat a) => Maybe Int -> a -> ShowS
+
+-- | Show a signed 'RealFloat' value
+-- using standard decimal notation (e.g. @245000@, @0.0015@).
+--
+-- In the call @'showFFloat' digs val@, if @digs@ is 'Nothing',
+-- the value is shown to full precision; if @digs@ is @'Just' d@,
+-- then at most @d@ digits after the decimal point are shown.
showFFloat :: (RealFloat a) => Maybe Int -> a -> ShowS
+
+-- | Show a signed 'RealFloat' value
+-- using standard decimal notation for arguments whose absolute value lies
+-- between @0.1@ and @9,999,999@, and scientific notation otherwise.
+--
+-- In the call @'showGFloat' digs val@, if @digs@ is 'Nothing',
+-- the value is shown to full precision; if @digs@ is @'Just' d@,
+-- then at most @d@ digits after the decimal point are shown.
showGFloat :: (RealFloat a) => Maybe Int -> a -> ShowS
showEFloat d x = showString (formatRealFloat FFExponent d x)
-- ---------------------------------------------------------------------------
-- Integer printing functions
+-- | Shows a /non-negative/ 'Integral' number using the base specified by the
+-- first argument, and the character representation specified by the second.
showIntAtBase :: Integral a => a -> (Int -> Char) -> a -> ShowS
showIntAtBase base toChr n r
| base <= 1 = error ("Numeric.showIntAtBase: applied to unsupported base " ++ show base)
c = toChr (fromIntegral d)
r' = c : r
-showHex, showOct :: Integral a => a -> ShowS
+-- | Show /non-negative/ 'Integral' numbers in base 16.
+showHex :: Integral a => a -> ShowS
showHex = showIntAtBase 16 intToDigit
+
+-- | Show /non-negative/ 'Integral' numbers in base 8.
+showOct :: Integral a => a -> ShowS
showOct = showIntAtBase 8 intToDigit
projects / ghc-base.git / blobdiff