Fast F#: Intro to Maps

The Map collection in F# is an immutable Key/Value collection. Let's learn how to work with them!
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[@ricosaupe]

Great explaining as always. This is interesting. This is not even complaining. Its just removing the first bit and replacing it with the last one.
let a = Map [ 1, "a"; 2, "b";1,"c" ]
a[1]
> let a = Map [ 1, "a"; 2, "b";1,"c" ]
- a[1];;
val a: Map = map [(1, "c"); (2, "b")]
val it: string = "c"
But why ist that?

[@FastFSharp]

Because when you are creating a map, the "last write wins". If you have several instances of the same key, that last key/value pair will be what is stored in the Map.