Combinations.fs

module Engine.Functions

let rec Calculate columns = 
    match columns with
    | h::[] -> [ [ h ] ]
    | h::t -> 
        let x = Calculate t
        List.fold (fun acc elem -> (h::elem)::acc) ([h]::x) x
    | [] -> []
    
    
    
let result = Calculate ["A"; "B"; "C"]

List.iter (fun x -> (printfn "%s" (List.fold (+) "" x))) result


(*
Gives
  AC                                                                                                                                                                                                                                                      
  AB                                                                                                                                                                                                                                                      
  ABC                                                                                                                                                                                                                                                     
  A                                                                                                                                                                                                                                                       
  BC                                                                                                                                                                                                                                                      
  B                                                                                                                                                                                                                                                       
  C    
*)