Replaced DisplayAble instance for Rational with auxiliary function rounding to Fixed E3

messages/uniworx/de.msg

@@ -316,9 +316,9 @@ Correctors: Korrektoren
 CorState: Status
 CorByTut: Zuteilung nach Tutorium
 CorProportion: Anteil
-CorByProportionOnly proportion@Rational: #{display proportion} Anteile
+CorByProportionOnly proportion@Rational: #{rationalToFixed3 proportion} Anteile
-CorByProportionIncludingTutorial proportion@Rational: #{display proportion} Anteile - Tutorium
+CorByProportionIncludingTutorial proportion@Rational: #{rationalToFixed3 proportion} Anteile - Tutorium
-CorByProportionExcludingTutorial proportion@Rational: #{display proportion} Anteile + Tutorium
+CorByProportionExcludingTutorial proportion@Rational: #{rationalToFixed3 proportion} Anteile + Tutorium
 
 RowCount count@Int64: #{count} #{pluralDE count "passender Eintrag" "passende Einträge"} insgesamt
 DeleteRow: Entfernen

src/Foundation.hs

@@ -350,6 +350,12 @@ instance HasResolution a => ToMessage (Fixed a) where
   toMessage = toMessage . showFixed True
 
 
+-- Do not use toMessage on Rationals and round them automatically. Instead, use rationalToFixed3 (declared in src/Utils.hs) to convert a Rational to Fixed E3!
+-- instance ToMessage Rational where
+--   toMessage = toMessage . fromRational'
+--     where fromRational' = fromRational :: Rational -> Fixed E3
+
+
 newtype ErrorResponseTitle = ErrorResponseTitle ErrorResponse
 embedRenderMessageVariant ''UniWorX ''ErrorResponseTitle ("ErrorResponseTitle" <>)
 

src/Model/Types/Common.hs

@@ -16,7 +16,6 @@ import qualified Yesod.Auth.Util.PasswordStore as PWStore
 type Count  = Sum Integer
 type Points = Centi
 
-
 type Email           = Text
 
 type SchoolName      = CI Text
@@ -32,4 +31,4 @@ type PWHashAlgorithm = ByteString -> PWStore.Salt -> Int -> ByteString
 type InstanceId      = UUID
 type ClusterId       = UUID
 type TokenId         = UUID
-type TermCandidateIncidence = UUID
+type TermCandidateIncidence = UUID

src/Utils.hs

@@ -30,7 +30,6 @@ import Text.Blaze (Markup, ToMarkup)
 
 import Data.Char (isDigit, isSpace, isAscii)
 import Data.Text (dropWhileEnd, takeWhileEnd, justifyRight)
-import Numeric (showFFloat)
 
 import Data.Set (Set)
 import qualified Data.Set as Set
@@ -248,21 +247,8 @@ class DisplayAble a where
   default display :: Show a => a -> Text
   display = pack . show
 
-instance DisplayAble Rational where
+rationalToFixed3 :: Rational -> Fixed E3
-  display r = showFFloat (Just 2) (rat2float r) ""
+rationalToFixed3 = fromRational
-      & pack
-      & dropWhileEnd ('0'==)
-      & dropWhileEnd ('.'==)
-    where
-      rat2float :: Rational -> Double
-      rat2float = fromRational
-
-{- We do not want DisplayAble for every Show-Class:
-   We want to explicitly verify that the resulting text can be displayed to the User!
-   For example: UTCTime values were shown without proper format rendering!
-instance {-# OVERLAPPABLE #-} Show a => DisplayAble a where -- The easy way out of UndecidableInstances (TypeFamilies would have been proper, but are much more complicated)
-  display = pack . show
--}
 
 textPercent :: Real a => a -> Text -- slow, maybe use Data.Double.Conversion.Text.toFixed instead?
 textPercent x = lz <> pack (show rx) <> "%"