FloatingHex 0.2 → 0.3

raw patch · 4 files changed

+49/−16 lines, 4 filesPVP ok

version bump matches the API change (PVP)

API changes (from Hackage documentation)

Files

• CHANGES.md +9/−1
• Data/Numbers/FloatingHex.hs +33/−12
• FloatingHex.cabal +2/−2
• README.md +5/−1

@@ -1,7 +1,15 @@ * Hackage: <http://hackage.haskell.org/package/FloatingHex> * GitHub:  <http://github.com/LeventErkok/FloatingHex/> -* Latest Hackage released version: 0.2, 2017-01-14+* Latest Hackage released version: 0.3, 2017-01-15++### Version 0.3, 2017-01-15++  * Bump up template-haskell dependency to >= 2.10. As noted by Herbert Valerio Riedel,+    FloatingHex fails to compile with older versions.++  * Make the double->float conversions more robust, by avoiding the rational route.+    (Avoids issues in https://ghc.haskell.org/trac/ghc/ticket/3676)  ### Version 0.2, 2017-01-14 

@@ -17,27 +17,48 @@ import Data.Char  (toLower) import Data.Ratio ((%)) import Numeric    (showHex, floatToDigits)+import GHC.Float  import qualified Language.Haskell.TH.Syntax as TH import           Language.Haskell.TH.Quote +-- | Due to intricacies of conversion between+-- float/doubles (see <https://ghc.haskell.org/trac/ghc/ticket/3676>), we explicitly introduce+-- a class to do the reading properly.+class RealFloat a => FloatingHexReader a where+   -- | Convert a hex-float to a Real-Float, if possible+   readHFloat :: String -> Maybe a++-- | The Float instance+instance FloatingHexReader Float where+   readHFloat s = double2Float `fmap` readHFloatAsDouble s++-- | The Double instance+instance FloatingHexReader Double where+   readHFloat = readHFloatAsDouble+ -- | Read a float in hexadecimal binary format. Supports negative numbers, and nan/infinity as well. -- For regular usage, the quasiquoter (`hf`) should be employed. But this function can be handy for -- programmatic interfaces.-readHFloat :: RealFloat a => String -> Maybe a-readHFloat = cvt+readHFloatAsDouble :: String -> Maybe Double+readHFloatAsDouble = cvt   where cvt ('-' : cs) = ((-1) *) `fmap` go cs         cvt cs         = go cs          go "NaN"      = Just $ 0/0         go "Infinity" = Just $ 1/0-        go cs         = (fromRational . toRational) `fmap` parseHexFloat cs+        go cs         = parseHexFloat cs  -- | Turn a hexadecimal float to an internal double, if parseable. Does not support the leading--- sign bit.+-- '-' bit, although it does allow a leading +. (The former is best done out of the quasiquote,+-- since TH does not cannot represent negative 0! See <https://ghc.haskell.org/trac/ghc/ticket/13124>+-- for why we avoid this here.) parseHexFloat :: String -> Maybe Double-parseHexFloat = go0 . map toLower-  where go0 ('0':'x':rest) = go1 rest+parseHexFloat = goS . map toLower+  where goS ('+':rest) = go0 rest+        goS cs         = go0 cs++        go0 ('0':'x':rest) = go1 rest         go0 _              = Nothing          go1 cs = case break (== 'p') cs of@@ -60,12 +81,12 @@          val :: Integer -> Int -> Integer -> Double         val a b e-          | e > 0 = fromRational $ (top * expt) % bot-          | True  = fromRational $ top % (expt * bot)-          where top, bot, expt :: Integer-                top  = a-                bot  = 16 ^ b-                expt =  2 ^ abs e+          | e > 0 = fromRational $ (top * power) % bot+          | True  = fromRational $ top % (power * bot)+          where top, bot, power :: Integer+                top   = a+                bot   = 16 ^ b+                power =  2 ^ abs e  -- | A quasiquoter for hexadecimal floating-point literals. -- See: <http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf>, pages 57-58.

@@ -1,5 +1,5 @@ Name:                FloatingHex-Version:             0.2+Version:             0.3 Synopsis:            Read and write hexadecimal floating point numbers Description:         Read and write hexadecimal floating point numbers. Provides a quasiquoter for                      entering hex-float literals, and a function for printing them in hexadecimal.@@ -26,5 +26,5 @@ Library   ghc-options     : -Wall   default-language: Haskell2010-  Build-Depends   : base >= 4 && < 5, template-haskell+  Build-Depends   : base >= 4 && < 5, template-haskell >= 2.10   Exposed-modules : Data.Numbers.FloatingHex

@@ -39,4 +39,8 @@ test = showHFloat [hf|0x1.f44abd5aa7ca4p+25|] "" ``` -(Note that while the quasiquoter allows for floating-point patterns, it is usually not a good idea to have floating-point literals used in pattern matching.)+(Note that while the quasiquoter allows for floating-point patterns, it is usually not a good idea to use floating-point literals in pattern matching.)++### Thanks+The following people reported bugs, provided comments/feedback, or contributed to the development of+FloatingHex in various ways: Herbert Valerio Riedel.