6d91b78 · streamly · git.iko.soy

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Convert to Rational before converting to Double

6d91b78Harendra Kumar3 years ago

core/src/Streamly/Internal/Unicode/Parser.hs+24−8

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unifiedsplit

@@ -51,6 +51,9 @@ module Streamly.Internal.Unicode.Parser

51 , double

52 , decimal

53 , hexadecimal

54+

55+ -- * Utilities

56+ , mkDouble

54 )

57 )

55where

58where

@@ -404,6 +407,19 @@ number = Parser (\s a -> return $ step s a) initial (return . extract)

404 extract (SPAfterExponent mult num decimalPlaces powerMult powerNum) =

407 extract (SPAfterExponent mult num decimalPlaces powerMult powerNum) =

405 Done 0 $ exitSPAfterExponent mult num decimalPlaces powerMult powerNum

408 Done 0 $ exitSPAfterExponent mult num decimalPlaces powerMult powerNum

406

409

410+-- XXX We can have a `realFloat` parser instead to parse any RealFloat value.

411+-- And a integral parser to read any integral value.

412+

413+-- | @mkDouble mantissa exponent@ converts a mantissa and exponent to a

414+-- 'Double' value equivalent to @mantissa * 10^exponent@. It does not check for

415+-- overflow, powers more than 308 will overflow.

416+{-# INLINE mkDouble #-}

417+mkDouble :: Integer -> Int -> Double

418+mkDouble mantissa power =

419+ if power > 0

420+ then fromRational (fromIntegral (mantissa * 10 ^ power))

421+ else fromRational (mantissa % 10 ^ (-power))

422+

407-- | Parse a decimal 'Double' value. This parser accepts an optional sign (+ or

423-- | Parse a decimal 'Double' value. This parser accepts an optional sign (+ or

408-- -) followed by at least one decimal digit. Decimal digits are optionally

424-- -) followed by at least one decimal digit. Decimal digits are optionally

409-- followed by a decimal point and at least one decimal digit after the point.

425-- followed by a decimal point and at least one decimal digit after the point.

@@ -414,6 +430,13 @@ number = Parser (\s a -> return $ step s a) initial (return . extract)

414--

430--

415-- >>> import qualified Streamly.Data.Stream as Stream

431-- >>> import qualified Streamly.Data.Stream as Stream

416-- >>> import qualified Streamly.Unicode.Parser as Unicode

432-- >>> import qualified Streamly.Unicode.Parser as Unicode

433+-- >>> import qualified Streamly.Internal.Unicode.Parser as Unicode (number, mkDouble)

434+--

435+-- Definition:

436+--

437+-- >>> double = uncurry Unicode.mkDouble <$> Unicode.number

438+--

439+-- Examples:

417--

440--

418-- >>> p = Stream.parse Unicode.double . Stream.fromList

441-- >>> p = Stream.parse Unicode.double . Stream.fromList

419--

442--

@@ -450,11 +473,4 @@ number = Parser (\s a -> return $ step s a) initial (return . extract)

450--

473--

451{-# INLINE double #-}

474{-# INLINE double #-}

452double :: Monad m => Parser Char m Double

475double :: Monad m => Parser Char m Double

453−double = fmap f number

476+double = uncurry mkDouble <$> number

454−

455− where

456−

457− f (m, e) =

458− if e > 0

459− then fromIntegral (m * 10 ^ e)

460− else fromRational (m % 10 ^ (-e))