module Validation =
        let regexCheck regex errorMessage value returnFun =
            if not <| Regex.IsMatch(value, regex) then
                Fail [errorMessage]
            else Ok <| returnFun value

    module Player =

        let createNickName nickName =
            Validation.regexCheck "^\w{1,20}$" "NickName is incorrect" nickName PlayerNickName

        let createFirstName firstName =
            Validation.regexCheck "^\w{1,20}$" "FirstName is incorrect" firstName PlayerFirstName

        let create nickName firstName =
            match createNickName nickName, createFirstName firstName with
            | Ok n, Ok f ->
                Ok { Id = NewPlayer
                     NickName = n
                     FirstName = f
                     JoinedCompanies = []
                     JoinedTeams = []
                     OwnedCompanies = []
                     OwnedTeams = [] }
            | Fail nl, Fail fl -> Fail <| nl @ fl
            | Fail nl, _ -> Fail nl
            | _, Fail fl -> Fail fl