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| author | Sven Tennie <sven.tennie@gmail.com> | 2018-12-26 12:04:36 +0100 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2019-01-06 07:27:09 -0500 |
| commit | 01b60b0e1ee57f882c5b729854343916c2295c51 (patch) | |
| tree | be1bfafd1e9a4dafc8c1a412b7c83fba3993b25a | |
| parent | c121e33f9b039acf2ac6939af8bfafe593560039 (diff) | |
| download | haskell-01b60b0e1ee57f882c5b729854343916c2295c51.tar.gz | |
Fix precedence handling for Data.Fixed's Show instance (#16031)
Use `showsPrec` instead of `show` to respect the precedence of the surrounding
context.
| -rw-r--r-- | libraries/base/Data/Fixed.hs | 2 | ||||
| -rw-r--r-- | libraries/base/tests/data-fixed-show-read.hs | 4 | ||||
| -rw-r--r-- | libraries/base/tests/data-fixed-show-read.stdout | 4 |
3 files changed, 9 insertions, 1 deletions
diff --git a/libraries/base/Data/Fixed.hs b/libraries/base/Data/Fixed.hs index 98acb76967..482ec0a694 100644 --- a/libraries/base/Data/Fixed.hs +++ b/libraries/base/Data/Fixed.hs @@ -158,7 +158,7 @@ showFixed chopTrailingZeros fa@(MkFixed a) = (show i) ++ (withDot (showIntegerZe -- | @since 2.01 instance (HasResolution a) => Show (Fixed a) where - show = showFixed False + showsPrec p n = showParen (p > 6 && n < 0) $ showString $ showFixed False n -- | @since 4.3.0.0 instance (HasResolution a) => Read (Fixed a) where diff --git a/libraries/base/tests/data-fixed-show-read.hs b/libraries/base/tests/data-fixed-show-read.hs index 7e947f466e..8766f0ae0c 100644 --- a/libraries/base/tests/data-fixed-show-read.hs +++ b/libraries/base/tests/data-fixed-show-read.hs @@ -21,6 +21,10 @@ main = do doit 38.001 print (read "-38" :: Centi) print (read "0.008" :: Fixed B7) print (read "-0.008" :: Fixed B7) + print $ show (Just (-1 :: Milli)) + print $ show (Just (1 :: Milli)) + print ((read $ show (Just (-1 :: Deci))) :: Maybe Deci) + print ((read $ show (Just (1 :: Deci))) :: Maybe Deci) doit :: Centi -> IO () doit c = do let s = show c diff --git a/libraries/base/tests/data-fixed-show-read.stdout b/libraries/base/tests/data-fixed-show-read.stdout index 4abb2d9676..4f24242da9 100644 --- a/libraries/base/tests/data-fixed-show-read.stdout +++ b/libraries/base/tests/data-fixed-show-read.stdout @@ -18,3 +18,7 @@ -38.00 0.008 -0.008 +"Just (-1.000)" +"Just 1.000" +Just (-1.0) +Just 1.0 |