Not sure whether or not this is a true bug or not, i.e. maybe it's caused by how date and time are dealt with in browsers, but it does lead to differences in how code works in local FSI vs online FSI.
Example code
open System
let x = DateTime.Now
let y = x.ToUniversalTime()
x.Equals y |> printfn "%A" // should be false
x = y |> printfn "%A" // should be false
printfn "%A" x // should be X hours before/after UTC
printfn "%A" y // should be UTC
Expected output
If you run this, it should output the following (which is what you'll see when running it locally in FSI, except that in UK the times may actually be equal, anywhere else they should be different):
However, it outputs this, note specifically the differences in how the %A outputs the time (which may be due to system wide settings on the machine, so not that big a deal), and, most importantly, that ToUniversalTime() did not change the time to UTC, instead the time variable remained unchanged.
true
true
Fri Feb 18 2022 17:09:41 GMT+0100 (Central European Standard Time)
Fri Feb 18 2022 17:09:41 GMT+0100 (Central European Standard Time)
Not sure whether or not this is a true bug or not, i.e. maybe it's caused by how date and time are dealt with in browsers, but it does lead to differences in how code works in local FSI vs online FSI.
Example code
Expected output
If you run this, it should output the following (which is what you'll see when running it locally in FSI, except that in UK the times may actually be equal, anywhere else they should be different):
Actual output on https://try.fsharp.org/
However, it outputs this, note specifically the differences in how the
%Aoutputs the time (which may be due to system wide settings on the machine, so not that big a deal), and, most importantly, thatToUniversalTime()did not change the time to UTC, instead the time variable remained unchanged.