isUpper is:exact

isUpper :: Char -> Bool
base Data.Char GHC.Unicode, protolude Protolude, Cabal-syntax Distribution.Compat.Prelude, ghc-internal GHC.Internal.Unicode, rebase Rebase.Prelude, cabal-install-solver Distribution.Solver.Compat.Prelude
Selects upper-case or title-case alphabetic Unicode characters (letters). Title case is used by a small number of letter ligatures like the single-character form of Lj. Note: this predicate does not work for letter-like characters such as: 'Ⓐ' (U+24B6 circled Latin capital letter A) and 'Ⅳ' (U+2163 Roman numeral four). This is due to selecting only characters with the GeneralCategory UppercaseLetter or TitlecaseLetter. See isUpperCase for a more intuitive predicate. Note that unlike isUpperCase, isUpper does select title-case characters such as 'Dž' (U+01C5 Latin capital letter d with small letter z with caron) or 'ᾯ' (U+1FAF Greek capital letter omega with dasia and perispomeni and prosgegrammeni).
isUpper :: Char -> Bool
rio RIO.Char, base-prelude BasePrelude
Selects upper-case or title-case alphabetic Unicode characters (letters). Title case is used by a small number of letter ligatures like the single-character form of Lj.
isUpper :: Char -> Bool
word8 Data.Char8
isUpper :: Word8 -> Bool
word8 Data.Word8
isUpper :: T -> Bool
xml-basic Text.HTML.Basic.Character
isUpper :: Char -> Bool
unicode-data Unicode.Char.Case.Compat
Selects upper-case or title-case alphabetic Unicode characters (letters). Title case is used by a small number of letter ligatures like the single-character form of Lj. It matches characters with general category UppercaseLetter and TitlecaseLetter. See: isUpperCase for the full upper case predicate. 
isUpper c == Data.Char.isUpper c
isUpper :: Char -> Bool
text-latin1 Text.Ascii
Test if a character is an ASCII upper-case letter.
isUpper :: Char -> Bool
text-latin1 Text.Latin1
Test if a character is a Latin-1 upper-case letter.