Fix even (#3930).

plutus-tx/src/PlutusTx/Prelude.hs

@@ -1,4 +1,5 @@
 -- Need some extra imports from the Prelude for doctests, annoyingly
+{-# LANGUAGE NoImplicitPrelude #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# OPTIONS_GHC -Wno-unused-imports #-}
 {-# OPTIONS_GHC -fno-omit-interface-pragmas #-}
@@ -116,12 +117,8 @@ import           PlutusTx.Ratio       as Ratio
 import           PlutusTx.Semigroup   as Semigroup
 import           PlutusTx.Trace       as Trace
 import           PlutusTx.Traversable as Traversable
-import           Prelude              hiding (Applicative (..), Enum (..), Eq (..), Foldable (..), Functor (..),
-                                       Monoid (..), Num (..), Ord (..), Rational, Semigroup (..), Traversable (..), all,
-                                       and, any, concat, concatMap, const, curry, divMod, either, elem, error, filter,
-                                       fst, head, id, length, map, mapM_, max, maybe, min, not, notElem, null, or,
-                                       quotRem, reverse, round, sequence, snd, take, uncurry, zip, (!!), ($), (&&),
-                                       (++), (<$>), (||))
+import           Prelude              (Integer, dropWhile, flip, otherwise, return, until, zipWith, (.), (=<<), (>>),
+                                       (>>=))
 
 -- this module does lots of weird stuff deliberately
 {- HLINT ignore -}
@@ -181,6 +178,10 @@ quotient = Builtins.quotientInteger
 remainder :: Integer -> Integer -> Integer
 remainder = Builtins.remainderInteger
 
+{-# INLINABLE even #-}
+even :: Integer -> Bool
+even n = if modulo n 2 == 0 then True else False
+
 {-# INLINABLE fst #-}
 -- | Plutus Tx version of 'Data.Tuple.fst'
 fst :: (a, b) -> a