X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Numeric.hs;h=e24803e9e4dec6b3e24ab752b159e295faca7fe0;hb=3ca8aac28460d0dd34b8b17dc469117bae184596;hp=5603ae6c072c0e880a49c9147b35c7b6f1e036d5;hpb=bba5c1507d5742b71d045654b48e229f9cf1022d;p=haskell-directory.git

diff --git a/Numeric.hs b/Numeric.hs
index 5603ae6..e24803e 100644
--- a/Numeric.hs
+++ b/Numeric.hs
@@ -1,4 +1,4 @@
-{-# OPTIONS -fno-implicit-prelude #-}
+{-# OPTIONS_GHC -fno-implicit-prelude #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Numeric
@@ -10,40 +10,51 @@
 -- 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
-        showBin,          -- :: Integral a => a -> ShowS
 
 	showEFloat,       -- :: (RealFloat a) => Maybe Int -> 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
 
-	) where
+	-- * Miscellaneous
 
-import Data.Char
+        fromRat,          -- :: (RealFloat a) => Rational -> a
+
+	) where
 
 #ifdef __GLASGOW_HASKELL__
 import GHC.Base
@@ -55,6 +66,8 @@ import GHC.Show
 import Data.Maybe
 import Text.ParserCombinators.ReadP( ReadP, readP_to_S, pfail )
 import qualified Text.Read.Lex as L
+#else
+import Data.Char
 #endif
 
 #ifdef __HUGS__
@@ -66,14 +79,29 @@ import Hugs.Numeric
 -- -----------------------------------------------------------------------------
 -- 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
 
@@ -88,6 +116,8 @@ 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 ++
@@ -103,6 +133,7 @@ readSigned readPos = readParen False read'
 -- -----------------------------------------------------------------------------
 -- 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"
@@ -130,8 +161,29 @@ showInt n cs
 	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)
@@ -142,36 +194,26 @@ showGFloat d x =  showString (formatRealFloat FFGeneric d x)
 -- ---------------------------------------------------------------------------
 -- Integer printing functions
 
-showIntAtBase :: Integral a => a -> (a -> Char) -> a -> ShowS
+-- | 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
-  | n < 0  = error ("Numeric.showIntAtBase: applied to negative number " ++ show n)
-  | otherwise = 
-    case quotRem n base of { (n', d) ->
-    let c = toChr d in
-    seq c $ -- stricter than necessary
-    let
-	r' = c : r
-    in
-    if n' == 0 then r' else showIntAtBase base toChr n' r'
-    }
-
+  | base <= 1 = error ("Numeric.showIntAtBase: applied to unsupported base " ++ show base)
+  | n <  0    = error ("Numeric.showIntAtBase: applied to negative number " ++ show n)
+  | otherwise = showIt (quotRem n base) r
+   where
+    showIt (n,d) r = seq c $ -- stricter than necessary
+      case n of
+        0 -> r'
+	_ -> showIt (quotRem n base) r'
+     where
+      c  = toChr (fromIntegral d) 
+      r' = c : r
+
+-- | Show /non-negative/ 'Integral' numbers in base 16.
 showHex :: Integral a => a -> ShowS
-showHex n r = 
- showString "0x" $
- showIntAtBase 16 (toChrHex) n r
- where  
-  toChrHex d
-    | d < 10    = chr (ord '0' + fromIntegral d)
-    | otherwise = chr (ord 'a' + fromIntegral (d - 10))
+showHex = showIntAtBase 16 intToDigit
 
+-- | Show /non-negative/ 'Integral' numbers in base 8.
 showOct :: Integral a => a -> ShowS
-showOct n r = 
- showString "0o" $
- showIntAtBase 8 (toChrOct) n r
- where toChrOct d = chr (ord '0' + fromIntegral d)
-
-showBin :: Integral a => a -> ShowS
-showBin n r = 
- showString "0b" $
- showIntAtBase 2 (toChrOct) n r
- where toChrOct d = chr (ord '0' + fromIntegral d)
+showOct = showIntAtBase 8  intToDigit