在不使用ad-hoc解析器实现的情况下反序列化许多网络消息(Deserializing many network messages without using an ad-hoc parser implementation)

 我有一个关于反序列化的问题。 我可以设想使用Data.Data，Data.Typeable或GHC.Generics的解决方案，但我很好奇它是否可以在没有泛型，SYB或元编程的情况下完成。 
 
 问题描述： 
 
 给定已知包含本地定义的代数数据类型字段的[String]列表，我想反序列化[String]以构造目标数据类型。 我可以编写一个解析器来执行此操作，但我正在寻找一种通用解决方案，它将反序列化为程序中定义的任意数量的数据类型，而无需为每种类型编写解析器。 通过知道代数类型的值构造函数的数量和类型，就像对每个字符串执行读取以生成构建类型所需的适当值一样简单。 但是，我不想使用泛型，反射，SYB或元编程（除非它不可能）。 
 
 假设我有大约50种与此类似的定义（所有简单的代数类型由基本原语组成（没有嵌套或递归类型，只是基元的不同组合和排序）： 
 
data NetworkMsg = NetworkMsg { field1 :: Int, field2 :: Int, field3 :: Double}

data NetworkMsg2 = NetworkMsg2 { field1 :: Double, field2 :: Int, field3 :: Double }
 
 我可以使用我在每个[String]之前解析的标记ID来确定与我通过网络收到的[String]相关联的数据类型。 
 
 可能的推测解决方案路径： 
 
 由于数据构造函数是Haskell中的第一类值，并且实际上具有类型 - 可以将NetworkMsg构造函数视为函数，例如： 
 
NetworkMsg :: Int -> Int -> Double -> NetworkMsg
 
 我可以使用uncurryN将此函数转换为元组的函数，然后将[String]复制到函数现在采用的相同形状的元组中吗？ 
 
NetworkMsg' :: (Int, Int, Double) -> NetworkMsg
 
 我认为这不会起作用，因为我需要知道值构造函数和类型信息，这需要Data.Typeable，反射或其他一些元编程技术。 
 
 基本上，我正在寻找许多类型的自动反序列化，而无需编写类型实例声明或在运行时分析类型的形状。 如果不可行，我会采用另一种方式。 

I have a question pertaining to deserialization. I can envision a solution using Data.Data, Data.Typeable, or with GHC.Generics, but I'm curious if it can be accomplished without generics, SYB, or meta-programming.
 
Problem Description:
 
Given a list of [String] that is known to contain the fields of a locally defined algebraic data type, I would like to deserialize the [String] to construct the target data type. I could write a parser to do this, but I'm looking for a generalized solution that will deserialize to an arbitrary number of data types defined within the program without writing a parser for each type. With knowledge of the number and type of value constructors an algebraic type has, it's as simple as performing a read on each string to yield the appropriate values necessary to build up the type. However, I don't want to use generics, reflection, SYB, or meta-programming (unless it's otherwise impossible).
 
Say I have around 50 types defined similar to this (all simple algebraic types composed of basic primitives (no nested or recursive types, just different combinations and orderings of primitives) :
 
data NetworkMsg = NetworkMsg { field1 :: Int, field2 :: Int, field3 :: Double}

data NetworkMsg2 = NetworkMsg2 { field1 :: Double, field2 :: Int, field3 :: Double }
 
I can determine the data-type to be associated with a [String] I've received over the network using a tag id that I parse before each [String].
 
Possible conjectured solution path:
 
Since data constructors are first-class values in Haskell, and actually have a type-- Can NetworkMsg constructor be thought of as a function, such as:
 
NetworkMsg :: Int -> Int -> Double -> NetworkMsg
 
Could I transform this function into a function on tuples using uncurryN then copy the [String] into a tuple of the same shape the function now takes?
 
NetworkMsg' :: (Int, Int, Double) -> NetworkMsg
 
I don't think this would work because I'd need knowledge of the value constructors and type information, which would require Data.Typeable, reflection, or some other metaprogramming technique.
 
Basically, I'm looking for automatic deserialization of many types without writing type instance declarations or analyzing the type's shape at run-time. If it's not feasible, I'll do it an alternative way.

原文：https://stackoverflow.com/questions/30549890