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%
% (c) The AQUA Project, Glasgow University, 1997-99
%
\section[Numeric]{Numeric interface}
Odds and ends, mostly functions for reading and showing
\tr{RealFloat}-like kind of values.
\begin{code}
{-# OPTIONS -fno-implicit-prelude #-}
module Numeric
( fromRat -- :: (RealFloat a) => Rational -> a
, showSigned -- :: (Real a) => (a -> ShowS) -> Int -> a -> ShowS
, readSigned -- :: (Real a) => ReadS a -> ReadS a
, showInt -- :: Integral a => a -> ShowS
, 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
, 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
, readFloat -- :: (RealFloat a) => ReadS a
, floatToDigits -- :: (RealFloat a) => Integer -> a -> ([Int], Int)
, lexDigits -- :: ReadS String
-- Implementation checked wrt. Haskell 98 lib report, 1/99.
) where
import PrelBase
import PrelMaybe
import PrelShow
import PrelArr
import PrelNum
import PrelNumExtra
import PrelRead
import PrelErr ( error )
\end{code}
\begin{code}
showInt :: Integral a => a -> ShowS
showInt i rs
| i < 0 = error "Numeric.showInt: can't show negative numbers"
| otherwise = go i rs
where
go n r =
case quotRem n 10 of { (n', d) ->
case chr (ord_0 + fromIntegral d) of { C# c# -> -- stricter than necessary
let
r' = C# c# : r
in
if n' == 0 then r' else go n' r'
}}
\end{code}
Controlling the format and precision of floats. The code that
implements the formatting itself is in @PrelNum@ to avoid
mutual module deps.
\begin{code}
showEFloat :: (RealFloat a) => Maybe Int -> a -> ShowS
showFFloat :: (RealFloat a) => Maybe Int -> a -> ShowS
showGFloat :: (RealFloat a) => Maybe Int -> a -> ShowS
showEFloat d x = showString (formatRealFloat FFExponent d x)
showFFloat d x = showString (formatRealFloat FFFixed d x)
showGFloat d x = showString (formatRealFloat FFGeneric d x)
\end{code}
|
