The isUpper function should return true for the '\9438' character

λ> toLower '\9438'
'\9438'
λ> toUpper '\9438'
'\9412'
λ> isUpper '\9438'
False
λ> isLower '\9438'
False

Here we can observe a contradiction. The toLower function does not alter its argument, but toUpper does, which tells us that the character 1) has the notion of case 2) it must be lower-cased. On the other hand, both isUpper and isLower functions return False for \9438 suggesting that it has no notion of case.

Apparently, \9438 is lower-cased and \9412 is its upper-cased version indeed:

λ> putStrLn "\9438"
ⓞ
λ> putStrLn "\9412"
Ⓞ

Trac metadata

Trac field	Value
Version	8.2.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	libraries/base
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