This behavior mirrors the behavior on .NET; if you run this code in fsi, you will get:
1 2 3
System.NullReferenceException: Object reference not set to an instance of an object. at <StartupCode$FSI_0004>.$FSI_0004.main@() Stopped due to error
The following returns undefined where I would expect 0.
1 2 3
let test () : int =
let a2 = Array2D.zeroCreate 1 1
a2.[0,0]So it does. Thank you; I was misled by the name, examples for ints and not usually having to deal with null in F#. It makes sense in terms of how to initialise a value of R and for performance reasons in some cases.
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[<JavaScript>] module Test = type R = { A : int; B : int } let test () = let a2 = Array2D.zeroCreate 1 1 a2.[0,0].AUncaught TypeError: Cannot read property 'A' of undefined.
A workaround is to use
Array2D.init.