Comparing F# Map to Dictionary<TKey,TValue>

F# Map is equal to .NET BCL Dictionary<TKey,TValue> conceptually because they both implement .NET IDictionary<TKey,TValue>. But F# Map is semantically different from Dictionary<TKey,TValue>.

Note

Please do not confuse F# Map as type with F# Map as a module. F# Map as a module is called Map. From outside, it is called by referencing to the namespace of FSharp.Collection.Map module. The F# Map as a type is available from outside F#. The name is called FSharpMap.

From the performance perspective, it is still faster because of its immutability behavior.

From the correctness perspective, F# Map is enforcing us to be more correct because of the constrained key and value of the generic type parameter.

Let's look at the type definition signature of F# Map:

type Map<[<EqualityConditionalOn>]''Key, [<EqualityConditionalOn;ComparisonConditionalOn>]'Value when 'Key : comparison >(comparer: IComparer<''Key>, tree: MapTree...