Data.Typeable: types which should compare equal don't

Here are two ways to construct a TypeRep for the type () -> ():

Prelude> import Data.Typeable
Prelude Data.Typeable> let unitToUnit = typeOf (\() -> ())
Prelude Data.Typeable> let unitToUnit' = mkFunTy (typeOf ()) (typeOf ())

It seems to work:

Prelude Data.Typeable> unitToUnit
() -> ()
Prelude Data.Typeable> unitToUnit'
() -> ()

But the two TypeReps are not equal:

Prelude Data.Typeable> unitToUnit == unitToUnit'
False

Trac metadata

Trac field	Value
Version	7.4.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	libraries/base
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