NegativeLiterals -0.0 :: Double

Compare

rwbarton@morphism:~$ ghc-8.0.1 -e '-0.0'
-0.0
rwbarton@morphism:~$ ghc-8.0.1 -XNegativeLiterals -e '-0.0'
0.0

This behavior is logical, but unexpected. The logic is that with NegativeLiterals the literal -0.0 means fromRational ((-0)%0), which equals fromRational 0, which for Double is positive zero, not negative zero.

But this seems unfortunate. Perhaps it would be best if -0.0 (or - applied to any other literal mathematically equal to zero) was desugared as negate 0.0 even under NegativeLiterals, since there doesn't seem to be any other reason to write -0.0.

Trac metadata

Trac field	Value
Version	8.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture