type MessageKey = { id: string; number: string }
 
type Substitution = Map<MessageKey, MessageKey>
 
type Message =
    { id: string
      number: string
      message: string
      message_v1: string
      message_v2: string
      message_v3: string
      message_v4: string }
 
let messagesToChange: Message list =
    [ { id = "SY"
        number = "530"
        message = "Es ist eine Ausnahme aufgetreten"
        message_v1 = ""
        message_v2 = ""
        message_v3 = ""
        message_v4 = "" }
      { id = "SY"
        number = "499"
        message = "A B C D"
        message_v1 = "A"
        message_v2 = "B"
        message_v3 = "C"
        message_v4 = "D" } ]
 
let substitutions: Substitution =
    Map
        [ ({ id = "SY"; number = "530" }, { id = "SY"; number = "000" })
          ({ id = "SY"; number = "499" }, { id = "ABC"; number = "999" }) ]
 
let Key (message: Message) : MessageKey =
    { id = message.id
      number = message.number }
 
let replace (substitutions: Substitution) (message: Message) : Message =
    let r: MessageKey option = Map.tryFind (Key message) substitutions in
 
    match r with
    | Some(r) ->
        { message with
            id = r.id
            number = r.number }
    | None -> message
 
let result = List.map (replace substitutions) messagesToChange
 

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