round

Prelude> round 0.5
0
Prelude> round 1.5
2
Prelude> round 2.5
2
Prelude> round 3.5
4

WHAT THE FUCK

>>15
Dude, I was taught in the local equivalent of grade school that 0.5 rounds _up_ by convention.

Then again, 0.5 (and 1.5, 2.5 etc) are those numbers that you cannot have exactly using a floating-point representation. So in financial code it's better to use an epsilon-sensitive comparison thing and call floor or ceil by hand. ... actually, in financial code it's best not to use floating point types at all.