在内部使用列表时,未定义相互递归类型

时间:2018-05-30 19:30:32

标签: types f# recursive-type

我在编译位于here的旧F#项目时遇到问题。违规档案为here

它使用相互递归类型,并且正确定义了缩进。但是,在同一上下文/缩进级别上看不到EDNValueEDNValueParsed

module EDNParserTypes =
 type EDNException(message : string) = 
    inherit System.Exception(message)

 type QualifiedSymbol = 
    struct
        val prefix: string
        val name: string
        new (prefix, name) = {prefix = prefix; name = name}
        override this.ToString() = "QualifiedSymbol Prefix: " + this.prefix + " Name: " + this.name 
    end

 type EDNValue = EDNNil
                | EDNBoolean of bool
                | EDNString of string
                | EDNCharacter of char
                | EDNSymbol of QualifiedSymbol
                | EDNKeyword of QualifiedSymbol
                | EDNInteger of BigInteger
                | EDNFloat of double
                | EDNComment of string
                | EDNDiscard of EDNValueParsed
                | EDNTaggedValue of QualifiedSymbol * EDNValueParsed
                | EDNList of string list
                | EDNVector of string array
                | EDNMap of List<string>
                | EDNSet of List<string>
  and EDNValueParsed = 
    struct
        val line: int64
        val col: int64
        val ednValue: EDNValue
        new (ednValue, line, col) = { ednValue = ednValue; line = line; col = col }
        override this.ToString() = 
            sprintf "%A" this.ednValue
    end

之后定义的这两个函数,编译失败,因为EDNValueParsed不被视为已定义。 EDNParserTypes.fs(41,41): Error FS0039: The type 'EDNValueParsed' is not defined. (FS0039) (EDNReaderWriter)

let getLineColString (valueParsed : EDNValueParsed) =
    System.String.Format("line: {0}, column: {1}", valueParsed.line, valueParsed.col); 

let isNotCommentOrDiscard (v : EDNValueParsed) =
    match v.ednValue with 
    | EDNComment _ | EDNDiscard _ -> false
    | _ -> true

一个奇怪的事情,如果我删除该类型的列表部分定义,它不会失败(但显然在需要这些定义的其他地方失败)

删除此部分后,正确定义了类型:

   | EDNList of string list
   | EDNVector of string array
   | EDNMap of List<string>
   | EDNSet of List<string>

我错过了什么?

1 个答案:

答案 0 :(得分:1)

如果您有新版本的VS,则无法使用旧的“预安装”版本的FSharp.Core(4.0.0.0)。

所以,像这样引用:

<Reference Include="FSharp.Core, Version=4.0.0.0, Culture=neutral,
PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" />

将会破产。

我无法从问题中重现错误,但我得到的错误非常简单:

  

无法解析此链接。找不到程序集“FSharp.Core,Version = 4.0.0.0,Culture = neutral,PublicKeyToken = b03f5f7f11d50a3a,processorArchitecture = MSIL”

     

“FSharpList&lt;&gt;”类型在未引用的程序集中定义。您必须添加对程序集“FSharp.Core,Version = 4.3.0.0,Culture = neutral,PublicKeyToken = b03f5f7f11d50a3a”的引用

修正后的项目构建没有错误。