{-# LANGUAGE CPP #-}
{-# LANGUAGE UnicodeSyntax #-}
{-# LANGUAGE DeriveDataTypeable #-}
#if __GLASGOW_HASKELL__ >= 706
{-# LANGUAGE DeriveGeneric #-}
#endif

-- | Print fractions.
module Text.Printer.Fractional
  (
  -- * Positional numeral systems
    PositionalSystem(..)
  , BitSystem(..)
  , Binary(..)
  , Octal(..)
  , Decimal(..)
  , Hexadecimal(..)
  , LowHex(..)
  , UpHex(..)
  -- * Optionality characteristic
  , Optional(..)
  , isOptional
  , isRequired
  -- * Fraction printers
  , fraction'
  , fraction
  ) where

#if __GLASGOW_HASKELL__ >= 706
import GHC.Generics (Generic)
#endif
import Data.Typeable (Typeable)
import Data.Ix (Ix)
import Data.Monoid (mempty)
import Data.Ratio (numerator, denominator)
import Text.Printer
import Text.Printer.Integral

-- | Optionality characteristic.
data Optional = Optional
              | Required
              deriving ( Typeable
#if __GLASGOW_HASKELL__ >= 706
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#endif
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-- | True if the supplied value is 'Optional' and false otherwise.
isOptional ∷ Optional → Bool
isOptional :: Optional -> Bool
isOptional Optional
Optional = Bool
True
isOptional Optional
Required = Bool
False

-- | True if the supplied value is 'Required' and false otherwise.
isRequired ∷ Optional → Bool
isRequired :: Optional -> Bool
isRequired Optional
Optional = Bool
False
isRequired Optional
Required = Bool
True

-- | Print a fraction, writing the numerator and the denominator in
--   the specified positional numeral system.
fraction' ∷ (PositionalSystem s, Real α, Printer p)
          ⇒ s
          → p -- ^ Prefix for negative values
          → p -- ^ Zero printer
          → p -- ^ Prefix for positive values
          → p -- ^ Numerator/denominator separator
          → Optional -- ^ Whether to print invisible denominators
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-- | Print a fraction. The numerator and the denominator are written in the
--   decimal numeral system and separated by a slash. Negative values
--   are prefixed with a minus sign. Invisible denominators are omitted.
fraction ∷ (Real α, Printer p) ⇒ α → p
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