F# - What is array<'T>?

Question

In this previous question I learnt that in F# an array<'T> is not the same as System.Array .

VS tells me that array<'T> inherits System.Array and has the full name Microsoft.FSharp.Core.array<_> and some additional Interfaces.

However MSDN says that array<'T> is a type abbreviation of System.Array . And that it has the notation arr.[i] to get and set items.

So for my lesson, is array<'T> a type abbreviation that includes type extensions and additional Interfaces? Where is the best place to look this up ?

Answer 1

The type array<'T> is an abbreviation, but not for the base type System.Array but for another generic type that represents arrays in F#, which is written as 'T[] .

This means that

• System.Array is the non-generic base type (where you cannot use indexing and you can only get elements as objects)

• 'T[] and array<'T> mean exactly the same thing. They are the generic type which supports indexing and you get 'T values from it.