F＃类型声明可能ala Haskell？ [英] F# Type declaration possible ala Haskell?

问题描述

 在F＃ala Haskell中声明类型定义似乎是不可能的：
 'haskell type def：
 myFunc :: int  - > int 
  

我想在F＃中使用这种type-def风格--FSI很乐意回显回到我身边：

  fsi>让myType x = x +1 ;; 
 
 val myType：int  - > int 
  

我想在Haskell中明确F＃类型的def签名。有没有办法做到这一点？我想用F＃编写：

  //无效F＃
 myFunc：int  - > int 
 myFunc x = x * 2 
  

解决方案

如果要将可读类型声明与实现分开，可以使用'fsi'文件（F＃签名文件）。 'fsi'只包含类型，通常也包含注释 - 你可以在F＃库的源代码中看到一些很好的例子。您可以创建两个文件：

  // Test.fsi 
 val myFunc：int  - > int 
 
 // Test.fs 
 let myFunx x = x + 1 
  

这适用于已编译的项目，但您不能在F＃Interactive中轻松使用此方法。

I've looked a number of sources: it seems not possible to declare a type definition in F# ala Haskell:

' haskell type def:
myFunc :: int -> int

I'd like to use this type-def style in F#--FSI is happy to echo back to me:

fsi> let myType x = x +1;;

val myType : int -> int

I'd like to be explicit about the type def signature in F# as in Haskell. Is there a way to do this? I'd like to write in F#:

//invalid F#
myFunc : int -> int
myFunc x = x*2

解决方案

If you want to keep readable type declarations separately from the implementation, you can use 'fsi' files (F# Signature File). The 'fsi' contains just the types and usually also comments - you can see some good examples in the source of F# libraries. You would create two files like this:

// Test.fsi
val myFunc : int -> int

// Test.fs
let myFunx x = x + 1

This works for compiled projects, but you cannot use this approach easily with F# Interactive.

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