Functional Minesweeper in F# and C#

This project it is not about what it does, it's about code. The code of the first implementation is written in C#, but in a very functional programming manner - that's what some call "functionalish".

The second implementation is the port of the C# implementation into F#. Since I tried to stick to the functional paradigm in the original implementation the port turned out to be just a kind of "word by word translation".

Example:

        public GameState Undo()
        {
            var moves = _moves.Pop();
            return moves.IsEmpty
                ? this
                : new GameState(moves, CursorPosition);
        }

    member x.Undo = 
        match x.Moves with
        | [] -> x
        | _ -> 
            { Moves = x.Moves.Tail
              CursorPosition = x.CursorPosition }

Pure functional in C#

This experiment and my expirience showed that now-days you can stick to functiona paradigm while using a universal languages like Java or C#.

Beeing functional in C# ...

• ... is doable!
• ... means you don't have to lern a functional language, you can stay in C# to understand and practice the functional programming paradigm
• ... allows moving towards functional by rewriting non functional code gradually

, although it ...

• ... is much more verbose
• ... requeres discipline not to "relapse"

These recommendations will help you to stay functional in C# while making a switch-over to F# a NOP:

1. Design with right data structures - prefer Sequnces (IEnumerable), Maps (Dictionary), Linked Lists (Stack) over Arrays and ILists (C#)
2. Prefer Pure Functions see.: Introduction to Pure Functional Transformations C#
3. Prefer LINQ which easily maps to pipes in F# |>.
4. Avoid nested conditionals (if else), instead prefer ? : operators, switch case or type matching which all map to pattern matching in F#. See.: Pattern Matching in C#
5. Control mutable state by using immutable data structures. See.:System.Collections.Immutable
6. Use events only when you absolutely have to. If events are your primary data source consider processing them as an event streams. See.: Reactive-Extensions/Rx.NET
7. Make constructors dumb - use static builder methods.
8. Use simple while loops - they are easier to replace with a recursion.