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bad float to int conversion
websharper

Using this code:

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  let t = Date.Now()
  let x = t/32
  JavaScript.Console.Log("t = "+t.ToString())
  JavaScript.Console.Log("x = "+x.ToString())

produces

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  t = 1445122700705
  x = -2084555859

which is wrong I believe.

Seems like t/32 is translated to t/32>>0. It should translate to (t/32)|0 instead?

.

t/32>>0 and (t/32)|0 both only works on 32-bit integers. The problem here is that Date.Now() return type is defined as int in WebSharper.JavaScript binding, but in reality it is now bigger than 32-bit. Still it's simpler not to change it now as it is a breaking change, and is safe to use when you do not do divide it.

One solution: use As cast (which does nothing in JS transation) to int64 or float:

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let t = Date.Now() |> As<int64>
let x = t/32L
By on 10/19/2015 3:43 AM ()

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