unsafeClamp behaves incorrectly for NaN

[felixSchl]

unsafeClamp is supposed to catch NaNs and return 0.

purescript-integers/src/Data/Int.purs

Lines 64 to 72 in 3850da9

	-- | Convert an integral `Number` to an `Int`, by clamping to the `Int` range.
	-- | This function will return 0 if the input is `NaN` or an `Infinity`.
	unsafeClamp :: Number -> Int
	unsafeClamp x
	| x == infinity = 0
	| x == -infinity = 0
	| x >= toNumber top = top
	| x <= toNumber bottom = bottom
	| otherwise = fromMaybe 0 (fromNumber x)

On the surface this works, however, it only works because the PureScript compiler inlines the comparison operation thereby avoiding the Ord instance for numbers and integers and doing whatever the JS runtime does, instead. This my be good enough but it cost me quite a bit of time to track down when implementing a new backend since I considered inlining of operators a mere optimization that should not impact semantics. If the backend does not implement this optimization, case 3 hits, giving you top for Int

To recap, the behavior of NaN (in Js and C) is that it does not equal itself. So maybe we could add a seemingly redundant guard:

  | x != x = 0 -- NaN

[hdgarrood]

Thanks for the report. I agree.